Nonpoint source contamination of the Mississippi river and its tributaries by herbicides

USGS Publications Warehouse

Pereira, W.E.; Hostettler, F.D.

1993-01-01

A study of the Mississippi River and its tributaries during July-August 1991, October-November 1991, and April-May 1992 has indicated that the entire navigable reach of the river is contaminated with a complex mixture of agrochemicals and their transformation products derived from nonpoint sources. Twenty-three compounds were identified, including triazine, chloroacetanilide, thiocarbamate, phenylurea, pyridazine, and organophosphorus pesticides. The upper and middle Mississippi River Basin farm lands are major sources of herbicides applied to corn, soybeans, and sorghum. Farm lands in the lower Mississippi River Basin are a major source of rice and cotton herbicides. Inputs of the five major herbicides atrazine, cyanazine, metolachlor, alachlor, and simazine to the Mississippi River are mainly from the Minnesota, Des Moines, Missouri, and Ohio Rivers. Ratios of desethylatrazine/atrazine potentially are useful indicators of groundwater and surface water interactions in the Mississippi River. These ratios suggested that during baseflow conditions, there is a significant groundwater contribution to the river. The Mississippi River thus serves as a drainage channel for pesticide-contaminated surface and groundwater from the midwestern United States. Conservative estimates of annual mass transport indicated that about 160 t of atrazine, 71 t of cyanazine, 56 t of metolachlor, and 18 t of alachlor were discharged into the Gulf of Mexico in 1991.

Simulated ground-water flow and water quality of the Mississippi River alluvium near Burlington, Iowa, 1999

USGS Publications Warehouse

Boyd, Robert A.

2001-01-01

Water samples collected from the alluvium indicated ground water can be classified as a calcium-magnesium-bicarbonate type. Reducing conditions likely occur in some localized areas of the alluvium, as suggested by relatively large concentrations of dissolved iron (4,390 micrograms per liter) and manganese (2, 430 micrograms per liter) in some ground-water samples. Nitrite plus nitrate was detected at concentrations greater than or equal to 8 milligrams per liter in three samples collected from observation wells completed in close proximity to cropland; the nitrite plus nitrate concentration in one groundwater sample exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level for nitrate in drinking water (10 milligrams per liter as N). Triazine herbicides (atrazine, cyanazine, propazine, simazine, and selected degradation products) and chloroacetanilide herbicides (acetochlor, alachlor, and metolachlor) were detected in some water samples. A greater number of herbicide compounds were detected in surface-water samples than in ground-water samples. Herbicide concentrations typically were at least an order of magnitude greater in surfacewater samples than in ground-water samples. The Maximum Contaminant Level for alachlor (2 micrograms per liter) was exceeded in a sample from Dry Branch Creek at Tama Road and for atrazine (3 micrograms per liter) was exceeded in samples collected from Dry Branch Creek at Tama Road and the county drainage ditch at Tama Road.

Cytotoxicity of chloroacetanilide herbicide alachlor in HepG2 cells independent of CYP3A4 and CYP3A7.

PubMed

Miranda, Sonia R; Meyer, Sharon A

2007-05-01

Alachlor is cytotoxic to human hepatoblastoma HepG2s, a cell line that expresses constitutive CYP3A7 and dexamethasone (DEX)-inducible CYP3A4 and CYP3A7. CYP3A4 catalyzes alachlor N-dealkylation to 2-chloro-N-(2,6-diethylphenyl)acetamide (CDEPA), precursor of 2,6-diethylbenzoquinoneimine, putative reactive metabolite for rat nasal carcinogenicity. We hypothesized that HepG2 alachlor cytotoxicity would be mediated by CYP3A4/7 and increased with DEX. Here, we report time-dependent alachlor cytotoxicity (EC(50) approximately 500 microM and 264+/-17 microM at 6 and 24h, respectively) as assessed by lactate dehydrogenase leakage. DEX pretreatment (25 microM, 48 h) significantly increased CYP3A7-catalyzed luciferin 6' benzylether O-debenzylation, but had no effect on alachlor toxicity. Further, CYP3A4/7 inhibitor triacetyloleandomycin did not prevent, but rather potentiated, alachlor cytotoxicity. In agreement, CDEPA was less toxic than parent alachlor. HepG2 CYP3A4 activity was unaffected by 48 h DEX pretreatment; therefore, studies were done in DPX-2 cells, a HepG2 derivative engineered to overexpress pregnane-X receptor (PXR) that exhibits rifampicin (RIF)-inducible endogenous CYP3A4. Alachlor cytotoxicity in DPX-2 cells occurred over a concentration range equivalent to that in HepG2. CYP3A4 activity of DPX-2 cells treated with RIF (10 microM, 48 h) was twice that of untreated cells, but RIF did not increase alachlor toxicity. These results demonstrate that neither CYP3A4 nor CYP3A7 initiate a pathway leading to a toxic alachlor metabolite.

Development of sampling and analytical methods for concerted determination of commonly used chloroacetanilide, chlorotriazine, and 2,4-D herbicides in hand-wash, dermal-patch, and air samples.

PubMed

Tucker, S P; Reynolds, J M; Wickman, D C; Hines, C J; Perkins, J B

2001-06-01

Sampling and analytical methods were developed for commonly used chloroacetanilide, chlorotriazine, and 2,4-D herbicides in hand washes, on dermal patches, and in air. Eight herbicides selected for study were alachlor, atrazine, cyanazine, 2,4-dichlorophenoxyacetic acid (2,4-D), metolachlor, simazine, and two esters of 2,4-D, the 2-butoxyethyl ester (2,4-D, BE) and the 2-ethylhexyl ester (2,4-D, EH). The hand-wash method consisted of shaking the worker's hand in 150 mL of isopropanol in a polyethylene bag for 30 seconds. The dermal-patch method entailed attaching a 10-cm x 10-cm x 0.6-cm polyurethane foam (PUF) patch to the worker for exposure; recovery of the herbicides was achieved by extraction with 40 mL of isopropanol. The air method involved sampling with an OVS-2 tube (which contained an 11-mm quartz fiber filter and two beds of XAD-2 resin) and recovery with 2 mL of 10:90 methanol:methyl t-butyl ether. Analysis of each of the three sample types was performed by gas chromatography with an electron-capture detector. Diazomethane in solution was employed to convert 2,4-D as the free acid to the methyl ester in each of the three methods for ease of gas chromatography. Silicic acid was added to sample solutions to quench excess diazomethane. Limits of detection for all eight herbicides were matrix-dependent and, generally, less than 1 microgram per sample for each matrix. Sampling and analytical methods met NIOSH evaluation criteria for all herbicides in hand-wash samples, for seven herbicides in air samples (all herbicides except cyanazine), and for six herbicides in dermal-patch samples (all herbicides except cyanazine and 2,4-D). Speciation of 2,4-D esters and simultaneous determination of 2,4-D acid were possible without losses of the esters or of other herbicides (acetanilides and triazines) being determined.

Comparative responses of river biofilms at the community level to common organic solvent and herbicide exposure.

PubMed

Paule, A; Roubeix, V; Swerhone, G D W; Roy, J; Lauga, B; Duran, R; Delmas, F; Paul, E; Rols, J L; Lawrence, J R

2016-03-01

Residual pesticides applied to crops migrate from agricultural lands to surface and ground waters. River biofilms are the first aquatic non-target organisms which interact with pesticides. Therefore, ecotoxicological experiments were performed at laboratory scale under controlled conditions to investigate the community-level responses of river biofilms to a chloroacetanilide herbicide (alachlor) and organic solvent (methanol) exposure through the development referenced to control. Triplicate rotating annular bioreactors, inoculated with river water, were used to cultivate river biofilms under the influence of 1 and 10 μg L(-1) of alachlor and 25 mg L(-1) of methanol. For this purpose, functional (thymidine incorporation and carbon utilization spectra) and structural responses of microbial communities were assessed after 5 weeks of development. Structural aspects included biomass (chlorophyll a, confocal laser scanning microscopy) and composition (fluor-conjugated lectin binding, molecular fingerprinting, and diatom species composition). The addition of alachlor resulted in a significant reduction of bacterial biomass at 1 μg L(-1), whereas at 10 μg L(-1), it induced a significant reduction of exopolymer lectin binding, algal, bacterial, and cyanobacterial biomass. However, there were no changes in biofilm thickness or thymidine incorporation. No significant difference between the bacterial community structures of control and alachlor-treated biofilms was revealed by terminal restriction fragment length polymorphism (T-RFLP) analyses. However, the methanol-treated bacterial communities appeared different from control and alachlor-treated communities. Moreover, methanol treatment resulted in an increase of bacterial biomass and thymidine incorporation as well. Changes in dominant lectin binding suggested changes in the exopolymeric substances and community composition. Chlorophyll a and cyanobacterial biomass were also altered by methanol. This study suggested that the concentration-dependent effect of alachlor mainly remains limited to biomass and growth inhibition without apparent changes of structural and functional characteristics measured. Our work also establishes the potential toxic effects of organic solvents on river biofilm in ecotoxicological experiments. For the ecotoxicological experiments, the alternative of dissolution in organic solvent followed by its evaporation, depositing the chemical on a glass surface prior to dissolution in river water used here, appears to allow exposure while minimizing the effect of organic solvent.

The acetochlor registration partnership surface water monitoring program for four corn herbicides.

PubMed

Hackett, Amy G; Gustafson, David I; Moran, Sharon J; Hendley, Paul; van Wesenbeeck, Ian; Simmons, Nick D; Klein, Andrew J; Kronenberg, Joel M; Fuhrman, John D; Honegger, Joy L; Hanzas, John; Healy, David; Stone, Christopher T

2005-01-01

A surface drinking water monitoring program for four corn (Zea mays L.) herbicides was conducted during 1995-2001. Stratified random sampling was used to select 175 community water systems (CWSs) within a 12-state area, with an emphasis on the most vulnerable sites, based on corn intensity and watershed size. Finished drinking water was monitored at all sites, and raw water was monitored at many sites using activated carbon, which was shown capable of removing herbicides and their degradates from drinking water. Samples were collected biweekly from mid-March through the end of August, and twice during the off-season. The analytical method had a detection limit of 0.05 microg L(-1) for alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide] and 0.03 microg L(-1) for acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide], atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide]. Of the 16528 drinking water samples analyzed, acetochlor, alachlor, atrazine, and metolachlor were detected in 19, 7, 87, and 53% of the samples, respectively. During 1999-2001, samples were also analyzed for the presence of six major degradates of the chloroacetanilide herbicides, which were detected more frequently than their parent compounds, despite having higher detection limits of 0.1 to 0.2 microg L(-1). Overall detection frequencies were correlated with product use and environmental fate characteristics. Reservoirs were particularly vulnerable to atrazine, which exceeded its 3 microg L(-1) maximum contaminant level at 25 such sites during 1995-1999. Acetochlor annualized mean concentrations (AMCs) did not exceed its mitigation trigger (2 microg L(-1)) at any site, and comparisons of observed levels with standard measures of human and ecological hazards indicate that it poses no significant risk to human health or the environment.

Metolachlor and alachlor breakdown product formation patterns in aquatic field mesocosms

USGS Publications Warehouse

Graham, William H.; Graham, D.W.; DeNoyelles, Frank; Smith, Val H.; Larive, C.K.; Thurman, E.M.

1999-01-01

The transformation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)- N-(2-methoxy-1-methyl)ethyl)acetamide] and alachlor [2-chloro-N-(2,6- diethylphenyl)-N-methoxymethyl)acetamide] in aquatic systems was investigated using outdoor tank mesocosms. Metolachlor and alachlor levels and their ethane sulfonic acid (ESA) and oxanillic acid breakdown products were monitored over time under five experimental treatments (each in quadruplicate). Background water conditions were identical in all treatments with each treatment differing based on the level and type(s) of herbicide present. Treatments included a noherbicide control, 10 ??g/L metolachlor, 25 ??g/L metolachlor, 25 ??g/L alachlor, and 25 ??g/L alachlor plus 25 ??g/L metolachlor in combination. The experiment was initiated by adding herbicide(s) to the units to the target concentrations; herbicide and breakdown product levels and other chemical parameters were then monitored for 85 days. In general, metolachlor half-lives were longer than alachlor half-lives under all treatments, although the differences were not statistically significant. Metolachlor half-lives (??95% confidence limits) ranged from 33.0 d (??14.1 d) to 46.2 d (??40.0 d), whereas alachlor half- lives ranged from 18.7 d (??3.5 d) to 21.0 d (??6.5 d) for different treatments. Formation patterns of ESA were similar in all treatments, whereas oxanillic acid formation differed for the two herbicides. Alachlor oxanillic acid was produced in larger quantities than metolachlor oxanillic acid and either ESA under equivalent conditions. Our results suggest that the transformation pathways for alachlor and metolachlor in aquatic systems are similar and resemble the acetochlor pathway in soils proposed by Feng (Pestic. Biochem. Physiol. 1991, 34, 136); however, the oxanillic acid branch of the pathway is favored for alachlor as compared with metolachlor.The transformation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N- (2-methoxy-1-methylethy)acetamide] and alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] in aquatic systems was investigated using outdoor tank mesocosms. Metolachlor and alachlor levels and their ethane sulfonic acid (ESA) and oxanillic acid breakdown products were monitored over time under five experimental treatments (each in quadruplicate). Background water conditions were identical in all treatments with each treatment differing based on the level and type(s) of herbicide present. Treatments included a no-herbicide control, 10 ??g/L metolachlor, 25 ??g/L metolachlor, 25 ??g/L alachlor, and 25 ??g/L alachlor plus 25 ??g/L metolachlor in combination. The experiment was initiated by adding herbicide(s) to the units to the target concentrations; herbicide and breakdown product levels and other chemical parameters were then monitored for 85 days. In general, metolachlor half-lives were longer than alachlor half-lives under all treatments, although the differences were not statistically significant. Metolachlor half-lives (??95% confidence limits) ranged from 33.0 d (??14.1 d) to 46.2 d (??40.0 d), whereas alachlor half-lives ranged from 18.7 d (??3.5 d) to 21.0 d (??6.5 d) for different treatments. Formation patterns of ESA were similar in all treatments, whereas oxanillic acid formation differed for the two herbicides. Alachlor oxanillic acid was produced in larger quantities than metolachlor oxanillic acid and either ESA under equivalent conditions. Our results suggest that the transformation pathways for alachlor and metolachlor in aquatic systems are similar and resemble the acetochlor pathway in soils proposed by Feng; however, the oxanillic acid branch of the pathway is favored for alachlor as compared with metolachlor.

METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACENTANILIDE HERBICIDE DEGRADATION PRODUCTS

EPA Science Inventory

Introduction: Acetanilide herbicides are frequently applied in the U.S. on crops (corn, soybeans, popcorn, etc.) to control broadleaf and annual weeds. The acetanilide and acetamide herbicides currently registered for use in the U.S. are alachlor, acetochlor, metolachlor, propa...

Occurrence and load of selected herbicides and metabolites in the lower Mississippi River

USGS Publications Warehouse

Clark, G.M.; Goolsby, D.A.

2000-01-01

Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991-1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general, were present in the largest concentrations. Almost 80% of the annual herbicide load to the Gulf of Mexico occurred during the growing season from May to August. The concentrations and loads of alachlor in the Mississippi River decreased dramatically after 1993 in response to decreased use in the basin. In contrast, the concentrations and loads of acetochlor increased after 1994, reflecting its role as a replacement for alachlor. The peak annual herbicide load occurred in 1993, when approximately 640 metric tons (t) of atrazine, 320 t of cyanazine, 215 t of metolachlor, 53 t of simazine, and 50 t of alachlor were discharged to the Gulf of Mexico. The annual loads of atrazine and cyanazine were generally 1-2% of the amount annually applied in the Mississippi River drainage basin; the annual loads of acetochlor, alachlor, and metolachlor were generally less than 1%. Despite a reduction in atrazine use, historical data do not indicate a long-term downward trend in the atrazine load to the Gulf of Mexico. Although a relation (r2=0.62) exists between the atrazine load and stream discharge during May to August, variations in herbicide use and rainfall patterns within subbasins can have a large effect on herbicide loads in the Mississippi River Basin and probably explain a large part of the annual variation in atrazine load to the Gulf of Mexico. Copyright (C) 2000 Elsevier Science B.V.

Occurrence and load of selected herbicides and metabolites in the lower Mississippi River

USGS Publications Warehouse

Clark, Gregory M.; Goolsby, Donald A.

2000-01-01

Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991–1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general, were present in the largest concentrations. Almost 80% of the annual herbicide load to the Gulf of Mexico occurred during the growing season from May to August. The concentrations and loads of alachlor in the Mississippi River decreased dramatically after 1993 in response to decreased use in the basin. In contrast, the concentrations and loads of acetochlor increased after 1994, reflecting its role as a replacement for alachlor. The peak annual herbicide load occurred in 1993, when approximately 640 metric tons (t) of atrazine, 320 t of cyanazine, 215 t of metolachlor, 53 t of simazine, and 50 t of alachlor were discharged to the Gulf of Mexico. The annual loads of atrazine and cyanazine were generally 1–2% of the amount annually applied in the Mississippi River drainage basin; the annual loads of acetochlor, alachlor, and metolachlor were generally less than 1%. Despite a reduction in atrazine use, historical data do not indicate a long-term downward trend in the atrazine load to the Gulf of Mexico. Although a relation (r2=0.62) exists between the atrazine load and stream discharge during May to August, variations in herbicide use and rainfall patterns within subbasins can have a large effect on herbicide loads in the Mississippi River Basin and probably explain a large part of the annual variation in atrazine load to the Gulf of Mexico.

RESPONSES OF MOLECULAR INDICATORS OF EXPOSURE IN MESOCOSMS: COMMON CARP (CYPRINUS CARPIO) EXPOSED TO THE HERBICIDES ALACHLOR AND ATRAZINE

EPA Science Inventory

Common carp (Cyprinus carpio) were treated in aquatic mesocosms with a single pulse of the herbicides atrazine or alachlor to study the bioavailability and biological activity of these herbicides using molecular indicators: Liver vitellogenin gene expression in male fish for estr...

Comparative sensitivity of five species of macrophytes and six species of algae to atrazine, metribuzin, alachlor, and metolachlor

USGS Publications Warehouse

Fairchild, James F.; Ruessler, Shane; Carlson, A. Ron

1998-01-01

This study determined the relative sensitivity of five species of aquatic macrophytes and six species of algae to four commonly used herbicides (atrazine, metribuzin, alachlor, and metolachlor). Toxicity tests consisted of 96-h (duckweed and algae) or 14-d (submerged macrophytes) static exposures. The triazine herbicides (atrazine and metribuzin) were significantly more toxic to aquatic plants than were the acetanilide herbicides (alachlor and metolachlor). Toxicity studies ranked metribuzin > atrazine > alachlor > metolachlor in decreasing order of overall toxicity to aquatic plants. Relative sensitivities of macrophytes to these herbicides decreased in the order of Ceratophyllum > Najas > Elodea > Lemna > Myriophyllum. Relative sensitivities of algae to herbicides decreased in the order of Selenastrum > Chlorella > Chlamydomonas > Microcystis > Scenedesmus > Anabaena. Algae and macrophytes were of similar overall sensitivities to herbicides. Data indicated that Selenastrum, a commonly tested green alga, was generally more sensitive compared to other plant species. Lemna minor, a commonly tested floating vascular plant, was of intermediate sensitivity, and was fivefold less sensitive than Ceratophyllum, which was the most sensitive species tested. The results indicated that no species was consistently most sensitive, and that a suite of aquatic plant test species may be needed to perform accurate risk assessments of herbicides.

Ethylcellulose formulations for controlled release of the herbicide alachlor in a sandy soil.

PubMed

Sopeña, Fátima; Cabrera, Alegría; Maqueda, Celia; Morillo, Esmeralda

2007-10-03

The development of controlled-release formulations of alachlor to diminish its leaching in sandy soils, avoiding groundwater contamination and maintaining its efficacy, was studied. For this purpose, ethylcellulose (EC) microencapsulated formulations (MEFs) of alachlor were prepared under different conditions and applied to soil columns to study their mobility. The results show that in all cases the release into water of alachlor from MEFs was retarded when compared with commercial formulation. Total leaching losses in soil columns were reduced to 59% from 98%. The mobility of alachlor from EC microspheres into soil columns has been greatly diminished in comparison with its current commercial formulation (CF), above all with increasing EC/herbicide ratios. Distribution of alachlor applied as MEFs at different depths in the soil was higher in the soil surface (66.3-81.3% of herbicide applied at the first 12 cm). In contrast, the residues from CF along the complete soil column were only 20.4%. From the results of bioassays, MEFs showed a higher efficacy than CF at 30 days after the treatment. The use of ME formulations could provide an advantage in minimizing the risk of groundwater contamination by alachlor and reducing the application rates, as a result of maintaining the desired concentration of the herbicide in the top soil layer, obtaining longer periods of weed control.

IMPROVING STRUCTURE-LINKED ACCESS TO PUBLICLY AVAILABLE CHEMICAL TOXICITY INFORMATION

EPA Science Inventory

Hepatotoxicity of the Herbicide Alachlor Associated with Glutathione Depletion, Oxidative Damage and Protein S-Cysteinyl Adduction.

Toxicity of the herbicide alachlor (2-chloro-2',6'-diethtl-N-[methoxtmethtl]-acetanilide) has been attributed to cytochrome P450-dependent me...

ANALYTICAL METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACETANILIDE PESTICIDE TRANSFORMATION PRODUCTS

EPA Science Inventory

Acetanilide herbicides are frequently applied in the U.S. on crops (corn, soybeans, popcorn, etc.) to control broadleaf and annual weeds. The acetanilide herbicides currently registered for use in the U.S. are: alachlor, acetochlor, metolachlor, propachlor, dimethenamid and fluf...

ANALYTICAL METHOD DEVELOPMENT FOR ALACHLOR ESA AND OTHER ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

EPA Science Inventory

In 1998, USEPA published a Drinking Water Contaminant Candidate List (CCL) of 50 chemicals and 10 microorganisms. "Alachlor ESA and other acetanilide herbicide degradation products" is listed on the the 1998 CCL. Acetanilide degradation products are generally more water soluble...

Combining supercritical fluid extraction of soil herbicides with enzyme immunoassay analysis.

PubMed

Stearman, G K

2001-10-01

Supercritical fluid extraction (SFE) of soil herbicides followed by enzyme immunoassay analysis (EIA) is explained in a step-by-step process. Extracted herbicides, include 2,4-D, simazine, atrazine, and alachlor. The herbicide, trifluralin was not successfully analyzed by EIA because of crossreacting metabolites. Problems with SFE, including uneven packing of cells, leaks, uneven flow and clogging, can largely be eliminated as the method parameters are optimized. It was necessary to add modifiers including methanol or acetone to the SF CO2 to increase the solubility of the analytes. Detection limits of 2.5 ng/g soil for atrazine and alachlor and 15 ng/g soil for simazine and 2,4-D without concentration of the sample were achieved. Recoveries above 80% and relative standard deviations (RSDs) less than 15% for 2,4-D simazine, atrazine and alachlor were achieved. Atrazine and alachlor recoveries were above 90% with RSDs below 10%. Forty soil samples could be extracted and analyzed in an 8-h day.

A pesticide monitoring survey in rivers and lakes of northern Greece and its human and ecotoxicological risk assessment.

PubMed

Papadakis, Emmaluel N; Vryzas, Zisis; Kotopoulou, Athena; Kintzikoglou, Katerina; Makris, Konstantinos C; Papadopoulou-Mourkidou, Euphemia

2015-06-01

A pesticide monitoring study covering the main rivers and lakes of Northern Greece (Macedonia, Thrace and Thessaly) was undertaken. A total of 416 samples were collected over a 1.5-year sampling period (September 1999- February 2001) from six rivers and ten lakes. The water samples were analyzed with an off-line solid phase extraction technique coupled with a gas chromatography ion trap mass spectrometer using an analytical method for 147 pesticides and their metabolites, including organochlorines, organophosphates, triazines, chloroacetanilides, pyrethroids, carbamates, phthalimides and other pesticides (herbicides, insecticides and fungicides). Based on the pesticide survey results, a human health carcinogenic and non-carcinogenic risk assessment was conducted for adults and children. Ecotoxicological risk assessment was also conducted using default endpoint values and the risk quotient method. Results showed that the herbicides metolachlor, prometryn, alachlor and molinate, were the most frequently detected pesticides (29%, 12.5%, 12.5% and 10%, respectively). They also exhibited the highest concentration values, often exceeding 1 μg/L. Chlorpyrifos ethyl was the most frequently detected insecticide (7%). Seasonal variations in measured pesticide concentrations were observed in all rivers and lakes. The highest concentrations were recorded during May-June period, right after pesticide application. Concentrations of six pesticides were above the maximum allowable limit of 0.1 μg/L set for drinking water. Alachlor, atrazine and a-HCH showed unacceptable carcinogenic risk estimates (4.5E-06, 4.6E-06 and 1.3E-04, respectively). Annual average concentrations of chlorpyriphos ethyl (0.031 μg L), dicofol (0.01 μg/L), dieldrin (0.02 μg/L) and endosulfan a (0.065 μg/L) exceeded the EU environmental quality standards. The risk quotient estimates for the insecticides chorpyrifos ethyl, diazinon and parathion methyl and herbicide prometryn were above acceptable risk values. The coupling of monitoring data to probabilistic human and ecotoxicological risk estimates could find use by Greek regulatory authorities, proposing effective pollution management schemes. Copyright © 2015 Elsevier Inc. All rights reserved.

Transport and attenuation of chloroacetanilides in an agricultural headwater catchment

NASA Astrophysics Data System (ADS)

Lefrancq, Marie; Imfeld, Gwenaël; Millet, Maurice; Payraudeau, Sylvain

2015-04-01

Chloroacetanilides (e.g., S-metolachlor and acetochlor) are pre-emergent herbicides used on corn and sugar beet and are applied to bare soil, which is prone to runoff and erosion. Some of these herbicides are chiral and the commercial products can be isomerically enriched in the enantiomer-S compared to the enantiomer-R as an example S-metolachlor 80/20% S to R . Determination of the transport of these herbicides in the dissolved and particulate phases of runoff water and degradation in agricultural catchments is currently lacking. The objectives of this study were i) to quantify over an corn growing season the export of chloroacetanilides and their main degradation products (ethane sulfonic (ESA) and oxanilic acid (OXA) degradates of metolachlor (MESA and MOXA) and acetochlor (AcESA and AcOXA)) in an 47 ha agricultural head-catchment in the dissolved and particulate phases, and ii) to evaluate S-metolachlor biodegradation from its application on the field to its export from the catchment using enantiomer analysis. Runoff, erosion, hydrochemistry and chloroacetanilide transport were evaluated at both the plot and catchment scales. Our results showed that an important amount of the pesticide load is missed when only the dissolved concentration of the parent compound is analysed. The total export coefficients for S-metolachlor and acetochlor and their degradation products were 11.4 and 11.8%, respectively, which includes both the dissolved and particulate loads. The partitioning of S-metolachlor and acetochlor between the dissolved and particulate phases varied widely over time and was linked to the suspended solid concentrations. Detection of S-metolachlor degradation products in runoff water was more frequent compared to that of acetochlor degradation products. Enrichment up to 37% of R-metolachlor was observed during the corn growing season, supporting enantioselective degradation of S-metolachlor. Our field study indicates the potential of enantiomer analyses for assessing chloroacetanilide biodegradation and could be complemented with laboratory benchmark studies on enantiomeric fractionation during chloroacetanilide degradation combined with an analysis of the degradation products to evaluate the extent of biodegradation in agro-ecosystems. We anticipate that our results will be a starting point for better understanding and predicting transport and degradation of chloroacetanilides at the agricultural catchment scale.

Impact of glyphosate-tolerant soybean and glufosinate-tolerant corn production on herbicide losses in surface runoff.

PubMed

Shipitalo, Martin J; Malone, Robert W; Owens, Lloyd B

2008-01-01

Residual herbicides used in the production of soybean [Glycine max (L.) Merr] and corn (Zea mays L.) are often detected in surface runoff at concentrations exceeding their maximum contaminant levels (MCL) or health advisory levels (HAL). With the advent of transgenic, glyphosate-tolerant soybean and glufosinate-tolerant corn this concern might be reduced by replacing some of the residual herbicides with short half-life, strongly sorbed, contact herbicides. We applied both herbicide types to two chiseled and two no-till watersheds in a 2-yr corn-soybean rotation and at half rates to three disked watersheds in a 3-yr corn/soybean/wheat (Triticum aestivum L.)-red clover (Trifolium pratense L.) rotation and monitored herbicide losses in runoff water for four crop years. In soybean years, average glyphosate loss (0.07%) was approximately 1/7 that of metribuzin (0.48%) and about one-half that of alachlor (0.12%), residual herbicides it can replace. Maximum, annual, flow-weighted concentration of glyphosate (9.2 microg L(-1)) was well below its 700 microg L(-1) MCL and metribuzin (9.5 microg L(-1)) was well below its 200 microg L(-1) HAL, whereas alachlor (44.5 microg L(-1)) was well above its 2 microg L(-1) MCL. In corn years, average glufosinate loss (0.10%) was similar to losses of alachlor (0.07%) and linuron (0.15%), but about one-fourth that of atrazine (0.37%). Maximum, annual, flow-weighted concentration of glufosinate (no MCL) was 3.5 microg L(-1), whereas atrazine (31.5 microg L(-1)) and alachlor (9.8 microg L(-1)) substantially exceeded their MCLs of 3 and 2 microg L(-1), respectively. Regardless of tillage system, flow-weighted atrazine and alachlor concentrations exceeded their MCLs in at least one crop year. Replacing these herbicides with glyphosate and glufosinate can reduce the occurrence of dissolved herbicide concentrations in runoff exceeding drinking water standards.

REMOVAL OF ALACHLOR FROM DRINKING WATER

EPA Science Inventory

Alachlor (Lasso) is a pre-emergent herbicide used in the production of corn and soybeans. U.S. EPA has studied control of alachlor in drinking water treatment processes to define treatability before setting maximum contaminant levels and to assist water utilities in selecting con...

Determination of alachlor and its sulfonic acid metabolite in water by solid-phase extraction and enzyme-linked immunosorbent assay

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.; Pomes, M.L.

1994-01-01

Solid-phase extraction (SPE) and enzyme-linked immunosorbent assay (ELISA) were combined for the trace analysis of the herbicide alachlor and its major soil metabolite, ethanesulfonic acid (ESA). The anti-alachlor antibody cross-reacted with ESA, which produced false-positive detections of alachlor in water samples by immunoassay screens. Alachlor and ESA were isolated from water by SPE on a C18 resin and eluted sequentially with ethyl acetate and methanol. Alachlor is soluble in ethyl acetate while the anionic ESA is not. Thus ESA remained adsorbed on the C18 resin and was eluted later with methanol. The combination of SPE with ELISA effectivety separated and quantified both alachlor and ESA using the same antibody for two ELISA methods. The general method may have applicability for the separation of other herbicides and their ionic metabolites. The SPE-ELISA method has a, detection limit of 0.01 ??g/L for alachlor and 0.05 ??g/L for ESA, with a precision of ?? 10%. Analyses of surface and ground water samples were confirmed by gas chromatography/mass spectrometry and high-performance liquid chromatography with photodiode-array detection. Results showed widespread occurrence of ESA in surface and ground water of the midwestern United States, with concentrations ranging from 10 ??g/L.

KINETICS OF ALACHLOR TRANSFORMATION AND IDENTIFICATION OF METABOLITES UNDER ANAEROBIC CONDITIONS. (R825549C037)

EPA Science Inventory

Alachlor is one of the two most commonly used herbicides in the United States. In the environment, little mineralization of this compound has been found to occur, and metabolites of alachlor may be formed and could accumulate. The objectives of this study were to determine the...

Evaluating the Influence of Drainage, Application, and Tillage Practices on the Dissipation of Chloroacetanilide Herbicides in Minnesota Soils

USDA-ARS?s Scientific Manuscript database

Acetochlor and metolachlor are herbicides used in Minnesota and the United States for the control of broadleaf and annual weeds in corn, soybean and other crops. Water monitoring studies have reported the occurrences of acetochlor, metolachlor and their breakdown products in both ground and surface ...

Multiple Pesticides Detoxification Function of Maize (Zea mays) GST34.

PubMed

Li, Dongzhi; Xu, Li; Pang, Sen; Liu, Zhiqian; Zhao, Weisong; Wang, Chengju

2017-03-08

ZmGST34 is a maize Tau class GST gene and was found to be differently expressed between two maize cultivars differing in tolerance to herbicide metolachlor. To explore the possible role of ZmGST34 in maize development, the expression pattern and substrate specificity of ZmGST34 were characterized by quantitative RT-PCR and heterologous expression system, respectively. The results indicated that the expression level of ZmGST34 was increased ∼2-5-fold per day during the second-leaf stage of maize seedling. Chloroacetanilide herbicides or phytohormone treatments had no influence on the expression level of ZmGST34, suggesting that ZmGST34 is a constitutively expressed gene in maize seedling. Heterologous expression in Escherichia coli and in Arabidopsis thaliana proved that ZmGST34 can metabolize most chloroacetanilide herbicides and increase tolerance to these herbicides in transgenic Arabidopsis thaliana. The constitutive expression pattern and broad substrate activity of ZmGST34 suggested that this gene may play an important role in maize development in addition to the detoxification of pesticides.

Risk assessment of herbicides and booster biocides along estuarine continuums in the Bay of Vilaine area (Brittany, France).

PubMed

Caquet, Th; Roucaute, M; Mazzella, N; Delmas, F; Madigou, C; Farcy, E; Burgeot, Th; Allenou, J-P; Gabellec, R

2013-02-01

A 2-year study was implemented to characterize the contamination of estuarine continuums in the Bay of Vilaine area (NW Atlantic Coast, Southern Brittany, France) by 30 pesticide and biocide active substances and metabolites. Among these, 11 triazines (ametryn, atrazine, desethylatrazine, desethylterbuthylazine, desisopropyl atrazine, Irgarol 1051, prometryn, propazine, simazine, terbuthylazine, and terbutryn), 10 phenylureas (chlortoluron, diuron, 1-(3,4-dichlorophenyl)-3-methylurea, fenuron, isoproturon, 1-(4-isopropylphenyl)-3-methylurea, 1-(4-isopropylphenyl)-urea, linuron, metoxuron, and monuron), and 4 chloroacetanilides (acetochlor, alachlor, metolachlor, and metazachlor) were detected at least once. The objectives were to assess the corresponding risk for aquatic primary producers and to provide exposure information for connected studies on the responses of biological parameters in invertebrate sentinel species. The risk associated with contaminants was assessed using risk quotients based on the comparison of measured concentrations with original species sensitivity distribution-derived hazardous concentration values. For EU Water Framework Directive priority substances, results of monitoring were also compared with regulatory Environmental Quality Standards. The highest residue concentrations and risks for primary producers were recorded for diuron and Irgarol 1051 in Arzal reservoir, close to a marina. Diuron was present during almost the all survey periods, whereas Irgarol 1051 exhibited a clear seasonal pattern, with highest concentrations recorded in June and July. These results suggest that the use of antifouling biocides is responsible for a major part of the contamination of the lower part of the Vilaine River course for Irgarol 1051. For diuron, agricultural sources may also be involved. The presence of isoproturon and chloroacetanilide herbicides on some dates indicated a significant contribution of the use of plant protection products in agriculture to the contamination of Vilaine River. Concentration levels and associated risk were always lower in estuarine sites than in the reservoir, suggesting that Arzal dam reduces downstream transfer of contaminants and favors their degradation in the freshwater part of the estuary. Results of the additional monitoring of two tidal streams located downstream of Arzal dam suggested that, although some compounds may be transferred to the estuary, their impact was probably very low. Dilution by marine water associated with tidal current was also a major factor of concentration reduction. It is concluded that the highest risks associated to herbicides and booster biocides concerned the freshwater part of the estuary and that its brackish/saltwater part was exposed to a moderate risk, although some substances may sometimes exhibit high concentration but mainly at low tide and on an irregular basis.

ACETANILIDE HERBICIDE DEGRADATION PRODUCTS BY LC/MS

EPA Science Inventory

Acetanilide herbicides are frequently applied in the U.S. on crops (corn, soybeans, popcorn, etc.) to control broadleaf and annual weeds. The acetanilide and acetamide herbicides currently registered for use in the U.S. are alachlor, acetochlor, metolachlor, propachlor, flufen...

Are shifts in herbicide use reflected in concentration changes in Midwestern rivers?

USGS Publications Warehouse

Battaglin, W.A.; Goolsby, D.A.

1999-01-01

In many Midwestern rivers, elevated concentrations of herbicides occur during runoff events for 1-3 months following application. The highest or 'peak' herbicide concentration often occurs during one of these runoff events. Herbicide concentrations in rivers are affected by a number of factors, including herbicide use patterns within the associated basin. Changing agricultural practices, reductions in recommended and permitted herbicide applications, shifts to new herbicides, and greater environmental awareness in the agricultural community have resulted in changes to herbicide use patterns. In the Midwestern United States, alachlor use was much larger in 1989 than in 1995, while acetochlor was not used in 1989, and commonly used in 1995. Use of atrazine, cyanazine, and metolachlor was about the same in 1989 and 1995. Herbicide concentrations were measured in samples from 53 Midwestern rivers during the first major runoff event that occurred after herbicide application (postapplication) in 1989, 1990, 1994, and 1995. The median concentrations of atrazine, alachlor, cyanazine, metribuzin, metolachlor, propazine, and simazine all were significantly higher in 1989/90 than in 1994/95. The median acetochlor concentration was higher in 1995 than in 1994. Estimated daily yields for all herbicides and degradation products measured, with the exception of acetochlor, were higher in 1989/90 than in 1994/95. The differences in concentration and yield do not always parallel changes in herbicide use, suggesting that other changes in herbicide or crop management are affecting concentrations in Midwestern rivers during runoff events.In many Midwestern rivers, elevated concentrations of herbicides occur during runoff events for 1-3 months following application. The highest or `peak' herbicide concentration often occurs during one of these runoff events. Herbicide concentrations in rivers are affected by a number of factors, including herbicide use patterns within the associated basin. Changing agricultural practices, reductions in recommended and permitted herbicide applications, shifts to new herbicides, and greater environmental awareness in the agricultural community have resulted in changes to herbicide use patterns. In the Midwestern United States, alachlor use was much larger in 1989 than in 1995, while acetochlor was not used in 1989, and commonly used in 1995. Use of atrazine, cyanazine, and metolachlor was about the same in 1989 and 1995. Herbicide concentrations were measured in samples from 53 Midwestern rivers during the first major runoff event that occurred after herbicide application (postapplication) in 1989, 1990, 1994, and 1995. The median concentrations of atrazine, alachlor, cyanazine, metribuzin, metolachlor, propazine, and simazine all were significantly higher in 1989/90 than in 1994/95. The median acetochlor concentration was higher in 1995 than in 1994. Estimated daily yields for all herbicides and degradation products measured, with the exception of acetochlor, were higher in 1989/90 than in 1994/95. The differences in concentration and yield do not always parallel changes in herbicide use, suggesting that other changes in herbicide or crop management are affecting concentrations in Midwestern rivers during runoff events.

METHOD 535: MEASUREMENT OF CHLOROACETANILIDE AND CHLOROACETAMIDE HERBICIDE DEGRADATES IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY (LC/MS/MS)

EPA Science Inventory

Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. The substitution of the sulfonic acid or the carbonic acid for the chlorine atom great...

Herbicides in the Pecatonica, Trempealeau, and Yahara Rivers in Wisconsin, May 1997-July 1998

USGS Publications Warehouse

Graczyk, David J.; Vanden Brook, James P.; Rheineck, Bruce D.

1999-01-01

In 1997, Wisconsin farmers applied 8.7 million pounds of herbicides on corn. The five most commonly applied herbicides (in lb (pounds) of active ingredient per acre) on corn in 1997 were atrazine, metolachlor, acetochlor, alachlor and cyanazine. A 1996 study by the U.S. Geological Survey (USGS) and the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) found that the most heavily applied agricultural herbicides were detected more frequently and at higher concentrations in the Pecatonica and Yahara Rivers in southern Wisconsin than the less heavily applied herbicides (Graczyk and Vanden Brook, 1997). The calculated herbicide loads a from May 15 to July 15, 1996 at the Pecatonica River ranged from 47.2 lb of alachlor to 484 lb of atrazine. For the Yahara River, loads ranged from 36.1 lb of alachlor to 289 lb of atrazine. The yields b (load per square mile) for atrazine were similar in the two water- sheds. This result was unexpected because the use of atrazine is prohibited on 94 percent of the Yahara River Watershed, but on only 4 percent of the Pecatonica River watershed. The unexpected atrazine result led to a continuation of the study in 1997 and 1998, when samples were collected again at the two sites sampled in 1996, and at a site in the upper third of the Yahara River Watershed that is entirely under atrazine use prohibition. For comparison purposes, a site in west-central Wisconsin also was sampled to determine herbicide loads and yields in another geographic area in the state

NOVEL CHROMATOGRAPHIC SEPARATION AND CARBON SOLID PHASE EXTRACTION OF ACETANILIDE HERBICIDE DEGRADATION PRODUCTS

EPA Science Inventory

Six acetanilide herbicides are currently registered for use in the U.S. Over the past several years, ethanesufonic acid (ESA) and oxanilic acid (OA) degradatoin products of these acetanilide herbicides have been found in U.S. ground waters and surface waters. "Alachlor ESA and ...

Degradation rates of alachlor, atrazine and bentazone in the profiles of Polish Luvisols

NASA Astrophysics Data System (ADS)

Paszko, Tadeusz; Muszyński, Paweł

2017-07-01

The degradation rates of three herbicides (alachlor, atrazine, and bentazone) were examined according to OECD Guideline 307 in three profiles of grey-brown podzolic soil (Luvisol) in a laboratory experiment. The aim of the experiment was to determine herbicide degradation parameters and their relationships with soil properties. Degradation processes were effectively described by a first-order model. However, in some cases, the best results were produced by bi-phasic kinetics (hockey-stick and bi-exponential model). The degradation rates of the tested herbicides at 25°C and 40% maximum water holding capacity, established based on half-life values in the Ap horizon, increased in the following order: atrazine (32.6-42.8 days) < bentazone (3.4-16.6 days < alachlor (4.4-5.7 days). The correlation analysis and the Principal Component Analysis revealed significant positive correlations between the herbicide degradation rates and the organic matter content of soils. The depth-dependent degradation factors obtained for topsoil and two subsoil horizons (1: 0.42: 0.11 - based on average values, and 1: 0.31: 0.12 - based on median values) reflect the degradation abilities of Polish Luvisols. The values noted are soil-specific; therefore, they can also be applied to other pesticides in Polish Luvisols.

Characterization of acetanilide herbicides degrading bacteria isolated from tea garden soil.

PubMed

Wang, Yei-Shung; Liu, Jian-Chang; Chen, Wen-Ching; Yen, Jui-Hung

2008-04-01

Three different green manures were added to the tea garden soils separately and incubated for 40 days. After, incubation, acetanilide herbicides alachlor and metolachlor were spiked into the soils, separately, followed by the isolation of bacteria in each soil at designed intervals. Several bacterial strains were isolated from the soils and identified as Bacillus silvestris, B. niacini, B. pseudomycoides, B. cereus, B. thuringiensis, B. simplex, B. megaterium, and two other Bacillus sp. (Met1 and Met2). Three unique strains with different morphologies were chosen for further investigation. They were B. megaterium, B. niacini, and B. silvestris. The isolated herbicide-degrading bacteria showed optimal performance among three incubation temperatures of 30 degrees C and the best activity in the 10 to 50 microg/ml concentration of the herbicide. Each bacterial strain was able to degrade more than one kind of test herbicides. After incubation for 119 days, B. cereus showed the highest activity to degrade alachlor and propachlor, and B. thuringiensis to degrade metolachlor.

The Response of Lemna minor to Mixtures of Pesticides That Are Commonly Used in Thailand.

PubMed

Tagun, Rungnapa; Boxall, Alistair B A

2018-04-01

In the field, aquatic organisms are exposed to multiple contaminants rather than to single compounds. It is therefore important to understand the toxic interactions of co-occurring substances in the environment. The aim of the study was to assess the effects of individual herbicides (atrazine, 2,4-D, alachlor and paraquat) that are commonly used in Thailand and their mixtures on Lemna minor. Plants were exposed to individual and binary mixtures for 7 days and the effects on plant growth rate were assesed based on frond area measurements. Experimental observations of mixture toxicity were compared with predictions based on single herbicide exposure data using concentration addition and independent action models. The single compound studies showed that paraquat and alachlor were most toxic to L. minor, followed by atrazine and then 2,4-D. For the mixtures, atrazine with 2,4-D appeared to act antagonistically, whereas alachlor and paraquat showed synergism.

Hydrologic data for a study of pre-Illinoian glacial till in Linn County, Iowa, water year 1991

USGS Publications Warehouse

Bowman, P.R.

1992-01-01

Herbicide concentrations in rainfall ranged from 0.05 to 1.3 micrograms per liter. Herbicides detected in the largest concentrations included alachlor, atrazine, and metolachlor. Metribuzin was the only herbicide detected in ground-water samples at a concentration of 0.10 micrograms per liter in water from one observation well.

Formation and transport of the sulfonic acid metabolites of alachlor and metolachlor in soil

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.

2001-01-01

Alachlor and metolachlor are dechlorinated and transformed into their corresponding ethane sulfonic acid (ESA) metabolites in soil. In a field-disappearance study, it was shown that alachlor ESA was formed at a faster rate and at concentrations 2-4 times higher than metolachlor ESA, conforming with the observed longer disappearance half-life of metolachlor (15.5 d) in the field as compared to alachlor (8 d). Runoff data also showed higher concentrations of alachlor ESA as compared to metolachlor ESA, even though they were applied at the same levels. Data from soil cores showed transport of the ESA compounds in soil to as far down as 75-90 cm below the surface, at concentrations ranging from less than 0.5 ??g/L to about 50 ??g/L. In contrast, no parent herbicide was detected at these depths. This observation correlates with the higher log KOC values for alachlor (3.33) and metolachlor (3.01) relative to their corresponding ESA metabolites, alachlor ESA (2.26), and metolachlor ESA (2.29).

Herbicides and nitrates in the Iowa River alluvial aquifer prior to changing land use, Iowa County, Iowa, 1996

USGS Publications Warehouse

Savoca, Mark E.; Tobias, Jennifer L.; Sadorf, Eric M.; Birkenholtz, Trevor L.

1997-01-01

Four herbicides (alachlor, atrazine, cyanazine, and metolachlor) and one nutrient (nitrate) were selected for study on the basis of frequent usage in Iowa and high detection rates in ground water (Detroy and Kuzniar, 1988). Alachlor was not detected at concentrations greater than the method detection limit (MDL). Atrazine was detected at concentrations greater than the MDL in samples from 48 percent of the 23 wells, cyanazine from 13 percent, metolachlor from 26 percent, and nitrate from 91 percent. None of the four herbicides were detected at concentrations greater than the respective U.S. Environmental Protection Agency's (USEPA) Maximum Contaminant Level (MCL) for drinking water. Thirteen percent of the samples had nitrate concentrations above the USEPA's MCL of 10 mg/L (milligrams per liter). Relations between constituent concentration and well depth were observed for specific constituents at individual well nests.

In vitro alachlor effects on reactive oxygen species generation, motility patterns and apoptosis markers in human spermatozoa.

PubMed

Grizard, Geneviève; Ouchchane, Lemlih; Roddier, Héléne; Artonne, Christine; Sion, Benoît; Vasson, Marie-Paule; Janny, Laurent

2007-01-01

Due to its extensive production and application, the toxicity of chloracetanilide herbicide alachlor[2-chloro-2',6'-diethyl-N-(methoxymethyl)-acetanilide] should be evaluated to establish minimum effects. In this study, we have examined the in vitro effects of alachlor on human sperm motion using a computer-assisted sperm analyser (CASA). An evaluation of both reactive oxygen species (ROS) and markers of apoptosis was also performed to investigate the mechanism by which alachlor modifies the sperm movement. After exposure up to 2 h to alachlor (0, 0.18, 0.37, 0.90 and 1.85 mM), the percentage of viable, motile spermatozoa and sperm velocities were concentration and/or time dependently decreased. The most sensitive parameters were progressive motility, mean average path velocity and mean straight velocity. Alachlor (1.85 mM) induced an increase in ROS production. A decrease of mitochondrial membrane potential (DeltaPsi(m)), an increase of both phosphatidylserine (PS) externalization and DNA fragmentation, which were concentration and/or time dependent, were also observed. It is possible that toxic effects of alachlor result in an oxidative stress which could act as a mediator of apoptosis. Alachlor could also contribute to some hypofertility cases.

Biodegradation of Metolachlor by Soil Bacteria and Yeast

USDA-ARS?s Scientific Manuscript database

Metolachlor (2-chloro-6’-ethyl-N-(2-methoxy-1-methylethyl) aceto-o-toluidide) is a pre-emergent chloroacetanilide herbicide used to control broadleaf and annual grassy weeds of corn, soybean, peanuts, sorghum, potatoes, cotton, and woody ornamental plants. It has been estimated that 15-24 and 20-24 ...

Water supply implications of herbicide sampling: Hydrologic conditions may affect concentrations of organonitrogen herbicides and may be important considerations in complying with drinking water regulations

USGS Publications Warehouse

Stamer, J.K.

1996-01-01

The temporal distribution of the herbicides alachlor, atrazine, cyanazine, and metolachlor was documented from September 1991 through August 1992 in the Platte River at Louisville, Neb., the drainage of the Central Nebraska Basins. Lincoln, Ornaha, and other municipalities withdraw groundwater for public supplies from the adjacent alluvium, which is hydraulically connected to the Platte River. Data were collected, in part, to provide information to managers, planners, and public utilities on the likelihood of water supplies being adversely affected by these herbicides. Three computational procedures - monthly means, monthly subsampling, and quarterly subsampling - were used to calculate annual mean herbicide concentrations. When the sampling was conducted quarterly rather than monthly, alachlor and atrazine concentrations were more likely to exceed their respective maximum contaminant levels (MCLs) of 2.0 μg/L and 3.0 μg/L, and cyanazine concentrations were more likely to exceed the health advisory level of 1.0 μg/L. The US Environmental Protection Agency has established a tentative MCL of 1.0 μg/L for cyanazine; data indicate that cyanazine is likely to exceed this level under most hydrologic conditions.

Pesticides and their metabolites in wells of Suffolk County, New York, 1998

USGS Publications Warehouse

Phillips, Patrick J.; Eckhardt, D.A.; Terracciano, S.A.; Rosenmann, Larry

1999-01-01

Five insecticide residues and 20 herbicide residues were detected in water samples collected from 50 shallow wells screened in the surficial sand and gravel aquifer in Suffolk County, Long Island in areas with known or suspected residues. Laboratory analytical methods with extremely low detection limits - from 0.001 to 0.2 ?g/L (micrograms per liter) - were used to analyze the samples for 60 pesticide residues. Forty-four of the samples contained at least one pesticide residue, and some samples contained as many as 11 different pesticides or pesticide metabolites. Only four water- quality standards were exceeded in the samples collected in this study. Dieldrin exceeded the New York State Class GA standard (0.004 ?g/L) in samples from eight wells. The Federal and New York State Maximum Contaminant Level for simazine (4 ?g/L) was exceeded in samples from two wells, and the State Class GA standard for simazine (0.5 ?g/L) was exceeded in samples from six wells. Federal water-quality standards have not been established for many of the compounds detected in this study, including herbicide metabolites. Maximum concentrations of four herbicide metabolites -metolachlor ESA (ethanesulfonic acid), metolachlor OA (oxanilic acid), and the alachlor metabolites alachlor ESA and alachlor OA -exceeded 20 ?g/L. The maximum concentration of one herbicide (tebuthiuron) exceeded 10 ?g/L, and the maximum concentration of three herbicides (simazine, metolachlor, and atrazine) and one herbicide metabolite (deisopropylatrazine) ranged from 1 to 10 ?g/L. The herbicide metolachlor, which is used on potato fields in Suffolk County, and its metabolites (metolachlor ESA and metolachlor OA) were most frequently detected in samples from agricultural areas. The herbicides simazine and tebuthiuron, which were used in utility rights-of-way, and the simazine metabolite deisopropylatrazine were detected at concentrations greater than 0.05 ?g/L most frequently in samples from residential and mixed land-use areas. The results of this investigation are not necessarily representative of conditions throughout the remainder of Long Island, because these samples were collected in areas of known or suspected residues.

Pesticides in surface water in the lower Illinois River basin, 1996-98

USGS Publications Warehouse

King, Robin B.

2003-01-01

Surface-water quality samples were collected from April 1996 to September 1998 from eight locations in the Lower Illinois River Basin, a study unit of the U.S. Geological Survey?s National Water-Quality Assessment program. The study area is approximately 15,600 square miles and encompasses most of central and western Illinois. The dominant land use is agricultural and most land is used for the production of corn and soybeans. About 6.9 million acres of corn and soybeans are planted annually in the lower Illinois River Basin. Conservation tillage, defined as mulch-till and no-till, is used on about 40 percent of the cropland in the study area, similar to the statewide average. Nearly 90 percent of the samples for pesticide analyses were collected at four sites: the Illinois River at Ottawa, the Illinois River at Valley City, the La Moine River at Colmar, and the Sangamon River at Monticello. Two hundred fifty-eight samples were collected and analyzed for various herbicides, insecticides, and herbicide transformation products (also referred to as degradates). Thirty-one pesticides were detected at concentrations above their respective method detection limit: 23 herbicides and 8 insecticides. An additional set of 34 samples was collected in the summer of 1998 for the analysis of herbicide transformation products. Nine herbicide transformation products were detected, all belonging to the chloroacetanilide or the triazine chemical class. Two herbicides, atrazine and cyanazine, exceeded the associated human health drinking-water criteria and the aquatic health-criteria. Atrazine was detected in all samples. Sixty percent of the samples (48 of 80) collected in the months of May and June had atrazine concentrations that exceeded the clean drinking- water standard of 3 micrograms per liter (mg/L). The average atrazine concentration in the May to June samples was about 7.0 mg/L. The maximum atrazine concentrations were 110 mg/L in the La Moine River at Colmar and 32 mg/L in the Sangamon River at Monticello. The maximum atrazine concentration in the lower Illinois River was 20 mg/L, measured at Valley City, although most of the relatively elevated concentrations in the Illinois River sites were in the range from 5 to 8 mg/L. The concentrations of the herbicide cyanazine exceeded the health advisory guideline of 1 mg/L in about 19 percent (15 of 80) of the May to June samples. The pesticides chlorpyrifos, diazinon, metolachlor, and 2,4-D exceeded aquatic health guidelines at various times from May to August. Three dominant factors that affect the presence of pesticides in streams are identified: the pesticide usage, the time-of-year (or season), and the flow condition. The pesticides with the highest usage--atrazine, metolachlor, cyanazine, and acetochlor--generally were the pesticides detected most frequently and at the highest concentrations. Notable exceptions to this general observation are alachlor and simazine, which did not have high usage but were detected frequently. The elevated pesticide concentrations were most affected by seasonality--most of these elevated concentrations were observed across all flow conditions during May to June. Flow conditions also affect pesticide concentrations, but not as much as seasonality. The maximum pesticide loads were observed between March and July on the Illinois River. The net contribution of pesticides applied in the study area to net increases in load indicates that only about 1-2 percent of the pesticides applied exit the basin through the Illinois River at Valley City. The chloroacetanilide-class transformation products observed in samples collected in summer 1998 persistently contained elevated concentrations relative to the associated parent pesticide compound at all locations and for all streamflow conditions. The concentration of the transformation product metolachlor ethane sulfonic acid (ESA) usually was about 10 times higher than the parent compound in the mainstem of the lower

Major herbicides in ground water: Results from the National Water-Quality Assessment

USGS Publications Warehouse

Barbash, J.E.; Thelin, G.P.; Kolpin, D.W.; Gilliom, R.J.

2001-01-01

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydrologic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides - atrazine (2-chloro-4-ethylamino-6-iso-propylamino-s-triazine), cyanazine (2-[4-chloro-6-ethylamino-l,3,5-triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis[ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N-[methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]. N-[2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxy-l- methylethyl]acetamide) - as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 ??g L-1 at 98% of the sites with detections, but exceeded drinking-water criteria (for atrazine) at two sites. In urban areas, frequencies of detection (at or above 0.01 ??g L-1) of atrazine, cyanazine, simazine, alachlor, and metolachlor in shallow ground water were positively correlated with their nonagricultural use nationwide (P < 0.05). Among different agricultural areas, frequencies of detection were positively correlated with nearby agricultural use for atrazine, cyanazine, alachlor, and metolachlor, but not simazine. Multivariate analysis demonstrated that for these five herbicides, frequencies of detection beneath agricultural areas were positively correlated with their agricultural use and persistence in aerobic soil. Acetochlor, an agricultural herbicide first registered in 1994 for use in the USA, was detected in shallow ground water by 1995, consistent with previous field-scale studies indicating that some pesticides may be detected in ground water within 1 yr following application. The NAWQA results agreed closely with those from other multistate studies with similar designs.

Herbicide and nitrate variation in alluvium underlying a cornfield at a site in Iowa County, Iowa

USGS Publications Warehouse

Kalkhoff, S.J.; Detroy, M.G.; Cherryholmes, K.; Kuzniar, R.L.

1992-01-01

A hydrologic investigation to determine vertical and seasonal variation of atrazine, alachlor, cyanazine, and nitrate at one location and to relate the variation to ground-water movement in the Iowa River alluvium was conducted in Iowa County, Iowa, from March 1986 to December 1987. Water samples were collected at discrete intervals through the alluvial sequence from the soil zone to the base of the aquifer. Alachlor, atrazine, and cyanazine were detected most frequently in the soil zone but also were present in the upper part of the alluvial aquifer. Alachlor was detected sporadically, whereas, atrazine, cyanazine, and nitrate were present throughout the year. In the alluvial aquifer, the herbicides generally were not detected during 1986 and were present in detectable concentrations for only a short period of time in the upper 1.6 meters of the aquifer during 1987. Nitrate was present throughout the alluvium and was stratified in the alluvial aquifer. The largest nitrate concentrations were detected in the middle part of the aquifer. Nitrate concentrations were variable only in the upper 2 meters of the aquifer. Vertical movement of herbicides and nitrate in the soil correlated with precipitation and degree of saturation. A clay layer retarded vertical movement of atrazine but not nitrate from the soil layer to the aquifer. Vertical movement could not account for the chemical variation in the alluvial aquifer.

Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries: Distribution, transport and fate

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.; ,

1992-01-01

The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6'-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be < 2% of the annual application of each herbicide in the Midwest.The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2???,6???-diethylacetanilide, 2-hydroxy-2???,6???-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987-1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be <2% of the annual application of each herbicide in the Midwest.

Comparative sensitivity of Selenastrum capricornutum and Lemna minor to sixteen herbicides

USGS Publications Warehouse

Fairchild, J.F.; Ruessler, D.S.; Haverland, P.S.; Carlson, A.R.

1997-01-01

Aquatic plant toxicity tests are frequently conducted in environmental risk assessments to determine the potential impacts of contaminants on primary producers. An examination of published plant toxicity data demonstrates that wide differences in sensitivity can occur across phylogenetic groups of plants. Yet relatively few studies have been conducted with the specific intent to compare the relative sensitivity of various aquatic plant species to contaminants. We compared the relative sensitivity of the algae Selenestrum capricornutum and the floating vascular plant Lemna minor to 16 herbicides (atrazine, metribuzin, simazine, cyanazine, alachlor, metolachlor, chlorsulfuron, metsulfuron, triallate, EPTC, trifluralin, diquat, paraquat, dicamba, bromoxynil, and 2,4-D). The herbicides studied represented nine chemical classes and several modes of action and were chosen to represent major current uses in the United States. Both plant species were generally sensitive to the triazines (atrazine, metribuzin, simazine, and cyanazine), sulfonureas (metsulfuron and chlorsulfuron), pyridines (diquat and paraquat), dinitroaniline (trifluralin), and acetanilide (alachlor and metolachlor) herbicides. Neither plant species was uniformly more sensitive than the other across the broad range of herbicides tested. Lemna was more sensitive to the sulfonureas (metsulfuron and chlorsulfuron) and the pyridines (diquat and parequat) than Selenastrum. However Selenastrum was more sensitive than Lemna to one of two thiocarbamates (triallate) and one of the triazines (cyanazine). Neither species was sensitive to selective broadleaf herbicides including bromoxynil, EPTC, dicamba, or 2,4-D. Results were not always predictable in spite of obvious differences in herbicide modes of action and plant phylogeny. Major departures in sensitivity of Selenastrum occurred between chemicals within individual classes of the triazine, acetanilide, and thiocarbamate herbicides. Results indicate that neither species is predictively most sensitive, and that a number of species including a dicot speciessuch as Myriophyllum are needed to perform accurate risk assessments of herbicides.

Degradation of alachlor and pyrimethanil by combined photo-Fenton and biological oxidation.

PubMed

Ballesteros Martín, M M; Sánchez Pérez, J A; García Sánchez, J L; Montes de Oca, L; Casas López, J L; Oller, I; Malato Rodríguez, S

2008-06-30

Biodegradability of aqueous solutions of the herbicide alachlor and the fungicide pyrimethanil, partly treated by photo-Fenton, and the effect of photoreaction intermediates on growth and DOC removal kinetics of the bacteria Pseudomonas putida CECT 324 are demonstrated. Toxicity of 30-120 mg L(-1) alachlor and pyrimethanil has been assayed in P. putida. The biodegradability of photocatalytic intermediates found at different photo-treatment times was evaluated for each pesticide. At a selected time during batch-mode phototreatment, larger-scale biodegradation kinetics were analysed in a 12 L bubble column bioreactor. Both alachlor and pyrimethanil are non-toxic for P. putida CECT 324 at the test concentrations, but they are not biodegradable. A approximately 100 min photo-Fenton pre-treatment was enough to enhance biodegradability, the biological oxidation response being dependent on the pesticide tested. The different alachlor and pyrimethanil respiration and carbon uptake rates in pre-treated solutions are related to change in the growth kinetics of P. putida. Reproducible results have shown that P. putida could be a suitable microorganism for determining photo-Fenton pre-treatment time.

Evaluation of microtiter-plate enzyme-linked immunosorbent assay for the analysis of triazine and chloroacetanilide herbicides in rainfall

USGS Publications Warehouse

Pomes, M.L.; Thurman, E.M.; Aga, D.S.; Goolsby, D.A.

1998-01-01

Triazine and chloroacetanilide concentrations in rainfall samples collected from a 23-state region of the United States were analyzed with microtiter-plate enzyme-linked immunosorbent assay (ELISA). Thirty-six percent of rainfall samples (2072 out of 5691) were confirmed using gas chromatography/mass spectrometry (GC/MS) to evaluate the operating performance of ELISA as a screening test. Comparison of ELISA to GC/MS results showed that the two ELISA methods accurately reported GC/MS results (m = 1), but with more variability evident with the triazine than with the chloroacetanilide ELISA. Bayes's rule, a standardized method to report the results of screening tests, indicated that the two ELISA methods yielded comparable predictive values (80%), but the triazine ELISA yielded a false- positive rate of 11.8% and the chloroacetanilide ELISA yielded a false- negative rate of 23.1%. The false-positive rate for the triazine ELISA may arise from cross reactivity with an unknown triazine or metabolite. The false-negative rate of the chloroacetanilide ELISA probably resulted from a combination of low sensitivity at the reporting limit of 0.15 ??g/L and a distribution characterized by 75% of the samples at or below the reporting limit of 0.15 ??g/L.Triazine and chloroacetanilide concentrations in rainfall samples collected from a 23-state region of the United States were analyzed with microtiter-plate enzyme-linked immunosorbent assay (ELISA). Thirty-six percent of rainfall samples (2072 out of 5691) were confirmed using gas chromatography/mass spectrometry (GC/MS) to evaluate the operating performance of ELISA as a screening test. Comparison of ELISA to GC/MS results showed that the two ELISA methods accurately reported GC/MS results (m = 1), but with more variability evident with the triazine than with the chloroacetanilide ELISA. Bayes's rule, a standardized method to report the results of screening tests, indicated that the two ELISA methods yielded comparable predictive values (80%), but the triazine ELISA yielded a false-positive rate of 11.8% and the chloroacetanilide ELISA yielded a false-negative rate of 23.1%. The false-positive rate for the triazine ELISA may arise from cross reactivity with an unknown triazine or metabolite. The false-negative rate of the chloroacetanilide ELISA probably resulted from a combination of low sensitivity at the reporting limit of 0.15 ??g/L and a distribution characterized by 75% of the samples at or below the reporting limit of 0.15 ??g/L.

Novel chromatographic separation and carbon solid-phase extraction of acetanilide herbicide degradation products.

PubMed

Shoemaker, Jody A

2002-01-01

One acetamide and 5 acetanilide herbicides are currently registered for use in the United States. Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of these acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. Alachlor ESA and other acetanilide degradation products are listed on the U.S. Environmental Protection Agency's (EPA) 1998 Drinking Water Contaminant Candidate List. Consequently, EPA is interested in obtaining national occurrence data for these contaminants in drinking water. EPA currently does not have a method for determining these acetanilide degradation products in drinking water; therefore, a research method is being developed using liquid chromatography/negative ion electrospray/mass spectrometry with solid-phase extraction (SPE). A novel chromatographic separation of the acetochlor/alachlor ESA and OA structural isomers was developed which uses an ammonium acetate-methanol gradient combined with heating the analytical column to 70 degrees C. Twelve acetanilide degradates were extracted by SPE from 100 mL water samples using carbon cartridges with mean recoveries >90% and relative standard deviations < or =16%.

Reconnaissance data for glyphosate, other selected herbicides, their degradation products, and antibiotics in 51 streams in nine midwestern states, 2002

USGS Publications Warehouse

Scribner, Elisabeth A.; Battaglin, William A.; Dietze, Julie E.; Thurman, E.M.

2003-01-01

Since 1989, the U.S. Geological Survey has conducted periodic reconnaissance studies of streams in the Midwestern United States to determine the geographic and seasonal distribution of herbicide compounds. These studies have documented that large amounts of acetochlor, alachlor, atrazine, cyanazine, metolachlor, and their degradation products are flushed into streams during post-application runoff. Additional studies show that peak herbicide concentrations tend to occur during the first runoff after herbicide application and that herbicide flushes can occur during runoff for several weeks to months following application. Since the first stream study conducted in 1989, several significant changes in herbicide use have occurred. The most substantial change is the tripling in the use of glyphosate during the past 5 years. Over this same time period (1997-2001), usage of acetochlor and atrazine increased slightly, whereas alachlor, cyanazine, and metolachlor usage decreased. During 2002, 154 samples were collected from 51 streams in nine Midwestern States during three periods of runoff. This report provides a compilation of the analytical results of five laboratory methods. Results show that glyphosate was detected in 55 (36 percent) of the samples, and aminomethylphosphonic acid (a degradation product of glyphosate) was detected in 107 (69 percent) of the samples. Atrazine, the most frequently detected herbicide, was found in 93 percent of the samples, followed by metolachlor, found in 73 percent of the samples; metolachlor ethanesulfonic acid (ESA) and oxanilic acid (OXA) were the most frequently detected herbicide degradation products, both being found in more than 95 percent of the samples. The data presented here are valuable for comparison with results from the earlier reconnaissance studies.

Laboratory and quality assurance protocols for the analysis of herbicides in ground water from the Management Systems Evaluation Area, Princeton, Minnesota

USGS Publications Warehouse

Larson, S.J.; Capel, P.D.; VanderLoop, A.G.

1996-01-01

Laboratory and quality assurance procedures for the analysis of ground-water samples for herbicides at the Management Systems Evaluation Area near Princeton, Minnesota are described. The target herbicides include atrazine, de-ethylatrazine, de-isopropylatrazine, metribuzin, alachlor, 2,6-diethylaniline, and metolachlor. The analytical techniques used are solid-phase extraction, and analysis by gas chromatography with mass-selective detection. Descriptions of cleaning procedures, preparation of standard solutions, isolation of analytes from water, sample transfer methods, instrumental analysis, and data analysis are included.

Pesticides in streams in the Tar-Pamlico drainage basin, North Carolina, 1992-94

USGS Publications Warehouse

Woodside, Michael D.; Ruhl, Kelly E.

2001-01-01

From 1992 to 1994, 147 water samples were collected at 5 sites in the Tar-Pamlico drainage basin in North Carolina and analyzed for 46 herbicides, insecticides, and pesticide metabolites as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Based on a common adjusted detection limit of 0.01 microgram per liter, the most frequently detected herbicides were metolachlor (84 percent), atrazine (78 percent), alachlor (72 percent), and prometon (57 percent). The insecticides detected most frequently were carbaryl (12 percent), carbofuran (7 percent), and diazinon (4 percent). Although the pesticides with the highest estimated uses generally were the compounds detected most frequently, there was not a strong correlation between estimated use and detection frequency. The development of statistical correlations between pesticide use and detection frequency was limited by the lack of information on pesticides commonly applied in urban and agricultural areas, such as prometon, chlorpyrifos, and diazinon, and the small number of basins included in this study. For example, prometon had the fourth highest detection frequency, but use information was not available. Nevertheless, the high detection frequency of prometon indicates that nonagricultural uses also contribute to pesticide levels in streams in the Tar-Pamlico drainage basin.Concentrations of the herbicides atrazine, alachlor, and trifluralin varied seasonally, with elevated concentrations generally occurring in the spring, during and immediately following application periods, and in the summer. Seasonal concentration patterns were less evident for prometon, diazinon, and chlorpyrifos. Alachlor is the only pesticide detected in concentrations that exceeded current (2000) drinking-water standards.

Automated solid-phase extraction of herbicides from water for gas chromatographic-mass spectrometric analysis

USGS Publications Warehouse

Meyer, M.T.; Mills, M.S.; Thurman, E.M.

1993-01-01

An automated solid-phase extraction (SPE) method was developed for the pre-concentration of chloroacetanilide and triazine herbicides, and two triazine metabolites from 100-ml water samples. Breakthrough experiments for the C18 SPE cartridge show that the two triazine metabolites are not fully retained and that increasing flow-rate decreases their retention. Standard curve r2 values of 0.998-1.000 for each compound were consistently obtained and a quantitation level of 0.05 ??g/l was achieved for each compound tested. More than 10,000 surface and ground water samples have been analyzed by this method.

Alachlor transformation patterns in aquatic field mesocosms under variable oxygen and nutrient conditions

USGS Publications Warehouse

Graham, D.W.; Miley, M.K.; Denoyelles, F.; Smith, Val H.; Thurman, E.M.; Carter, R.

2000-01-01

Alachlor is one of the most commonly used herbicides in both Europe and North America. Because of its toxic properties, its fate and attenuation in natural waters is practically important. This paper assesses factors that affect alachlor decay rate in aquatic systems using field-scale experimental units. In particular, we used field mesocosms (11.3 m3 outdoor fiberglass tanks) to examine the affect of oxygen level and other factors on decay rate in water columns. This is one of the first studies ever performed where diverse water column conditions have been successfully simulated using common mesocosm-scale facilities. Four treatments were assessed, including aerobic systems (aerobic); low nutrient, oxygen-stratified systems (stratified-LN); moderate nutrient, oxygen-stratified systems (stratified-HN); and anaerobic systems (anaerobic). The lowest half-lives were observed in the anaerobic units (9.7 days) followed by the aerobic (21 days), stratified-HN (22 days), and stratified-LN (46 days) units. Our results indicate that alachlor is transformed most rapidly under anaerobic conditions, although the ambient phosphorus level also appears to influence decay rate. In this study, two common alachlor breakdown products, ethane sulfonic acid (ESA) and oxanilic acid, were also monitored. Oxanilic acid was produced in greater quantities than ESA under all treatments with the highest levels being produced in the stratified-HN units. In general, our results suggest that previous laboratory data, which indicated that high rates of alachlor decay can occur under oxygen-free methanogenic conditions, is translatable to field-scale applications. Copyright (C) 2000 Elsevier Science Ltd.Alachlor is one of the most commonly used herbicides in both Europe and North America. Because of its toxic properties, its fate and attenuation in natural waters is practically important. This paper assesses factors that affect alachlor decay rate in aquatic systems using field-scale experimental units. In particular, we used field mesocosms (11.3 m3 outdoor fiberglass tanks) to examine the affect of oxygen level and other factors on decay rate in water columns. This is one of the first studies ever performed where diverse water column conditions have been successfully simulated using common mesocosm-scale facilities. Four treatments were assessed, including aerobic systems (aerobic); low nutrient, oxygen-stratified systems (stratified-LN); moderate nutrient, oxygen-stratified systems (stratified-HN); and anaerobic systems (anaerobic). The lowest half-lives were observed in the anaerobic units (9.7 days) followed by the aerobic (21 days), stratified-HN (22 days), and stratified-LN (46 days) units. Our results indicate that alachlor is transformed most rapidly under anaerobic conditions, although the ambient phosphorus level also appears to influence decay rate. In this study, two common alachlor breakdown products, ethane sulfonic acid (ESA) and oxanilic acid, were also monitored. Oxanilic acid was produced in greater quantities than ESA under all treatments with the highest levels being produced in the stratified-HN units. In general, our results suggest that previous laboratory data, which indicated that high rates of alachlor decay can occur under oxygen-free methanogenic conditions, is translatable to field-scale applications.Aquatic field mesocosms were used to examine the influence of DO concentration and the presence of nutrients on alachlor transformation. Four treatments were used: wholly aerobic water columns, thermally and oxygen stratified water columns with low nutrient levels, stratified water columns with moderate nutrient levels, and wholly anaerobic water columns. The anaerobic treatment produced the highest rate of alachlor decay, followed by the aerobic and stratified treatments. The lowest decay rate occurred in the aerobic, low-nutrient stratified units.

Occurrence of dichloroacetamide herbicide safeners and co-applied herbicides in midwestern U.S. streams

USGS Publications Warehouse

Woodward, Emily; Hladik, Michelle; Kolpin, Dana W.

2018-01-01

Dichloroacetamide safeners (e.g., AD-67, benoxacor, dichlormid, and furilazole) are co-applied with chloroacetanilide herbicides to protect crops from herbicide toxicity. While such safeners have been used since the early 1970s, there are minimal data about safener usage, occurrence in streams, or potential ecological effects. This study focused on one of these research gaps, occurrence in streams. Seven Midwestern U.S. streams (five in Iowa and two in Illinois), with extensive row-crop agriculture, were sampled at varying frequencies from spring 2016 through summer 2017. All four safeners were detected at least once; furilazole was the most frequently detected (31%), followed by benoxacor (29%), dichlormid (15%), and AD-67 (2%). The maximum concentrations ranged from 42 to 190 ng/L. Stream detections and concentrations of safeners appear to be driven by a combination of timing of application (spring following herbicide application) and precipitation events. Detected concentrations were below known toxicity levels for aquatic organisms.

Predicted impact of transgenic, herbicidetolerant corn on drinking water quality in vulnerable watersheds of the mid-western USA.

PubMed

Wauchope, R Don; Estes, Tammara L; Allen, Richard; Baker, James L; Hornsby, Arthur G; Jones, Russell L; Richards, R Peter; Gustafson, David I

2002-02-01

In the intensely farmed corn-growing regions of the mid-western USA, surface waters have often been contaminated by herbicides, principally as a result of rainfall runoff occurring shortly after application of these to corn and other crops. In some vulnerable watersheds, water quality criteria for chronic human exposure through drinking water are occasionally exceeded. We selected three settings representative of vulnerable corn-region watersheds, and used the PRZM-EXAMS model with the Index Reservoir scenario to predict corn herbicide concentrations in the reservoirs as a function of herbicide properties and use pattern, site characteristics and weather in the watersheds. We compared herbicide application scenarios, including broadcast surface pre-plant atrazine and alachlor applications with a glyphosate pre-plant application, scenarios in which losses of herbicides were mitigated by incorporation or banding, and scenarios in which only glyphosate or glufosinate post-emergent herbicides were used with corn genetically modified to be resistant to them. In the absence of drift, in almost all years a single runoff event dominates the input into the reservoir. As a result, annual average pesticide concentrations are highly correlated with annual maximum daily values. The modeled concentrations were generally higher than those derived from monitoring data, even for no-drift model scenarios. Because of their lower post-emergent application rates and greater soil sorptivity, glyphosate and glufosinate loads in runoff were generally one-fifth to one-tenth those of atrazine and alachlor. These model results indicate that the replacement of pre-emergent corn herbicides with the post-emergent herbicides allowed by genetic modification of crops would dramatically reduce herbicide concentrations in vulnerable watersheds. Given the significantly lower chronic mammalian toxicity of these compounds, and their vulnerability to breakdown in the drinking water treatment process, risks to human populations through drinking water would also be reduced.

Pesticide sorption and leaching potential on three Hawaiian soils.

PubMed

Hall, Kathleen E; Ray, Chittaranjan; Ki, Seo Jin; Spokas, Kurt A; Koskinen, William C

2015-08-15

On the Hawaiian Islands, groundwater is the principal source of potable water and contamination of this key resource by pesticides is of great concern. To evaluate the leaching potential of four weak acid herbicides [aminocyclopyrachlor, picloram, metsulfuron-methyl, biologically active diketonitrile degradate of isoxaflutole (DKN)] and two neutral non-ionizable herbicides [oxyfluorfen, alachlor], their sorption coefficients were determined on three prevalent soils from the island of Oahu. Metsulfuron-methyl, aminocylcopyrachlor, picloram, and DKN were relatively low sorbing herbicides (K(oc) = 3-53 mL g(-1)), alachlor was intermediate (K(oc) = 120-150 mL g(-1)), and oxyfluorfen sorbed very strongly to the three soils (K(oc) > 12,000 mL g(-1)). Following determination of K(oc) values, the groundwater ubiquity score (GUS) indices for these compounds were calculated to predicted their behavior with the Comprehensive Leaching Risk Assessment System (CLEARS; Tier-1 methodology for Hawaii). Metsulfuron-methyl, aminocyclopyrachlor, picloram, and DKN would be categorized as likely leachers in all three Hawaiian soils, indicating a high risk of groundwater contamination across the island of Oahu. In contrast, oxyfluorfen, regardless of the degradation rate, would possess a low and acceptable leaching risk due to its high sorption on all three soils. The leaching potential of alachlor was more difficult to classify, with a GUS value between 1.8 and 2.8. In addition, four different biochar amendments to these soils did not significantly alter their sorption capacities for aminocyclopyrachlor, indicating a relatively low impact of black carbon additions from geologic volcanic inputs of black carbon. Due to the fact that pesticide environmental risks are chiefly dependent on local soil characteristics, this work has demonstrated that once soil specific sorption parameters are known one can assess the potential pesticide leaching risks. Published by Elsevier Ltd.

Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain

USGS Publications Warehouse

Panno, S.V.; Kelly, W.R.

2004-01-01

This investigation was designed to estimate the mass loading of nitrate (NO3-) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3- and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate-nitrogen (NO3-N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3-N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 ??g/l and <0.01 to 0.98 ??g/l, respectively, with median concentrations of 0.48 and 0.12 ??g/l, respectively. Approximately 100,000 kg/yr of NO3-N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3- came from background sources and most of the remainder probably came from fertilizer. This represents a 21-31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8-5.8% of the applied atrazine, and 0.05-0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs. ?? 2004 Elsevier B.V. All rights reserved.

Herbicides and their transformation products in source-water aquifers tapped by public-supply wells in Illinois, 2001-02

USGS Publications Warehouse

Mills, Patrick C.; McMillan, William D.

2004-01-01

During 2001-02, ground-water samples were collected from 117 public-supply wells distributed throughout Illinois to evaluate the occurrence of herbicides and their transformation products in the State?s source-water aquifers. Wells were selected using a stratified-random method to ensure representation of the major types of source-water aquifers in the State. Samples were analyzed for 18 herbicides and 18 transformation products, including 3 triazine and 14 chloroacetanilide products. Herbicide compounds (field-applied parent herbicides and their transformation products) were detected in 34 percent of samples. A subset of samples was collected unfiltered to determine if analytical results for herbicides in unfiltered samples are similar to those in paired filtered samples and, thus, can be considered equally representative of herbicide concentrations in ground water supplied to the public. The study by the U.S. Geological Survey was done in cooperation with the Illinois Environmental Protection Agency. Parent herbicides were detected in only 4 percent of all samples. The six most frequently detected herbicide compounds (from 5 to 28 percent of samples) were chloroacetanilide transformation products. The frequent occurrence of transformation products and their higher concentrations relative to those of most parent herbicides confirm the importance of obtaining information on transformation products to understand the mobility and fate of herbicides in ground-water systems. No sample concentrations determined during this study exceeded current (2003) Federal or State drinking-water standards; however, standards are established for only seven parent herbicides. Factors related to the occurrence of herbicide compounds in the State?s source-water aquifers include unconsolidated and unconfined conditions, various hydrogeologic characteristics and well-construction aspects at shallow depths, and proximity to streams. Generally, the closer an aquifer (or well location) is to a recharge area and (or) the stronger the hydraulic connection between an aquifer and a recharge area, the younger the ground water and the more vulnerable the aquifer will be to contamination by herbicide compounds. The weak relation between current (2001) statewide application rates of herbicides and current (2001-02) occurrence of herbicide compounds in source-water aquifers indicates that additional factors must be considered when relating herbicide-application rates to occurrence. These factors include historical application rates and the mobility and persistence of the various herbicide compounds in ground-water systems. Frequency of detection and concentrations of herbicides compounds in the State?s source-water aquifers are indicated to be highest during the spring, when crops are planted and herbicides primarily are applied. Excess nitrate (concentrations of nitrate, as nitrogen, higher than 3 milligrams per liter) in ground water strongly indicates the co-occurrence of herbicide compounds. However, nitrate concentrations are not a reliable indicator of herbicide-compound concentrations. The inverse relation found between current use of land for corn and soybean production and current occurrence of herbicide compounds in underlying aquifers indicates that various factors, along with current agricultural land use, contribute to herbicide occurrence. These factors include, among others, land-use history, ground-water age, ground-water-flow patterns, geology, soil microbiology, and chemistry and persistence of the herbicide compounds. Detection of agriculture-specific herbicide compounds in 71 percent of samples from urban areas with no current or recent agricultural land use near the sampled wells indicates that recharge to certain high-capacity supply wells may originate at considerable distances (up to about 10 miles) from the wells. Essentially no difference was found between the analytical results for herbicides in paired unfiltered and filtered samples,

Occurrence of active and inactive herbicide ingredients at selected sites in Iowa

USGS Publications Warehouse

Wang, W.; Liszewski, M.; Buchmiller, R.; Cherryholmes, K.

1995-01-01

Herbicides were detected in 50% of water samples, ranging from 78% of water samples from the Ames site to 25% from the Walnut Creek site. Among herbicides detected, listed in decreasing order of frequency, were atrazine > alachlor > cyanazine > metolachlor > metribuzin. Volatile organic compounds were detected in 11% of water samples. Among the compounds detected, listed in decreasing order of frequency, were xylene > toluene > acetone. One sample contained a detectable amount of aliphatic compound(s), with the empirical formula of C8H18. Results from the Deer Creek site showed that herbicides were detected primarily in the top layer (1.2 m), whereas xylene and other alkylbenzenes were detected at 2.1 m or deeper. Apparently, physico-chemical and other factors are separating herbicides and volatile organic compounds in the shallow unsaturated zone.

Synthetic organic agrochemicals in the lower Mississippi River and its major tributaries--Distribution, transport and fate

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.

1992-01-01

The Mississippi River and its major tributaries transport herbicides and their degradation products from agricultural areas in the mid-western U.S.A. These compounds include atrazine and its degradation products (desethyl- and desisopropylatrazine), simazine, cyanazine, metolachlor, and alachlor and its degradation products (2-chloro-2′,6′-diethylacetanilide 2-hydroxy-2′,6′-diethylacetanilide and 2,6-diethylaniline). These compounds were identified and confirmed by gas chromatography-ion trap mass spectrometry. Loads of these compounds were determined during five sampling trips in 1987–1989. Stream loads of these compounds indicated that atrazine and metolachlor were relatively conservative in downstream transport. Alachlor and its degradation products were generated from point and non-point sources. Seasonal variations and hydrologic conditions controlled the loads of these compounds in the Mississippi River. Cross-channel mixing was slow downstream from major river confluences, possibly requiring several hundred kilometers of downriver transit for completion. The annual transport of these compounds into the Gulf of Mexico was estimated to be < 2% of the annual application of each herbicide in the Midwest.

Surface water-ground water interaction: Herbicide transport into municipal collector wells

USGS Publications Warehouse

Verstraeten, Ingrid M.; Carr, J.D.; Steele, G.V.; Thurman, E.M.; Bastian, K.C.; Dormedy, D.F.

1999-01-01

During spring runoff events, herbicides in the Platte River are transported through an alluvial aquifer into collector wells located on an island in the river in 6 to 7 d. During two spring runoff events in 1995 and 1996, atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] concentrations in water from these wells reached approximately 7 ??g/L, 70 times more than the background concentration in ground water. Concentrations of herbicides and metabolites in the collector wells generally were one-half to one-fifth the concentrations of herbicides in the river for atrazine, alachlor [2-chloro-2'-6'-diethyl-N-(methoxymethyl)-acetanilide], alachlor ethane-sulfonic acid (ESA) [2-((2,6-diethylphenyl) (methoxymethyl)amino)-2- oxoethane-sulfonic acid], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N- (2-methoxy-1-methylethyl)acetamide], cyanazine [2-((4-chloro-6-(ethyl-amino)- 1,3,5 triazin-2-yl)-amino)-2-methylpropionitrile], and acetochlor [2-chloro- N-(ethoxymethyl)-N-(2-ethyl-6methyl-phenyl) acetamide], suggesting that 20 to 50% river water could be present in the water from the collector wells, assuming no degradation. The effect of the river on the quality of water from the collector wells can be reduced through selective management of horizontal laterals of the collector wells. The quality of the water from the collector wells is dependent on the (i) selection of the collector well used, (ii) number and selection of laterals used, (iii) chemical characteristics of the contaminant, and (iv) relative mixing of the Platte River and a major upstream tributary.

Trends in concentrations and use of agricultural herbicides for Corn Belt rivers, 1996-2006

USGS Publications Warehouse

Vecchia, Aldo V.; Gilliom, Robert J.; Sullivan, Daniel J.; Lorenz, David L.; Martin, Jeffrey D.

2009-01-01

Trends in the concentrations and agricultural use of four herbicides (atrazine, acetochlor, metolachlor, and alachlor) were evaluated for major rivers of the Corn Belt for two partially overlapping time periods: 1996-2002 and 2000-2006. Trends were analyzed for 11 sites on the mainstems and selected tributaries in the Ohio, Upper Mississippi, and Missouri River Basins. Concentration trends were determined using a parametric regression model designed for analyzing seasonal variability, flow-related variability, and trends in pesticide concentrations(SEAWAVE-Q).TheSEAWAVE-Qmodel accounts for the effect of changing flow conditions in order to separate changes caused by hydrologic conditions from changes caused by other factors, such as pesticide use. Most of the trends in atrazine and acetochlor concentrations for both time periods were relatively small and nonsignificant, but metolachlor and alachlor were dominated by varying magnitudes of concentration downtrends. Overall, with trends expressed as a percent change per year, trends in herbicide concentrations were consistent with trends in agricultural use; 84 of 88 comparisons for different sites, herbicides, and time periods showed no significant difference between concentration trends and agricultural use trends. Results indicate that decreasing use appears to have been the primary cause for the concentration downtrends during 1996-2006 and that, while there is some evidence that nonuse management factors may have reduced concentrations in some rivers, reliably evaluating the influence of these factors on pesticides in large streams and rivers will require improved, basin-specific information on both management practices and use over time. ?? 2009 American Chemical Society.

Regional patterns of pesticide concentrations in surface waters of New York in 1997

USGS Publications Warehouse

Phillips, P.J.; Eckhardt, D.A.; Freehafer, D.A.; Wall, G.R.; Ingleston, H.H.

2002-01-01

The predominant mixtures of pesticides found in New York surface waters consist of five principal components. First, herbicides commonly used on corn (atrazine, metolachlor, alachlor, cyanazine) and a herbicide degradate (deethylatrazine) were positively correlated to a corn-herbicide component, and watersheds with the highest corn-herbicide component scores were those in which large amounts of row crops are grown. Second, two insecticides (diazinon and carbaryl) and one herbicide (prometon) widely used in urban and residential settings were positively correlated to an urban/residential component. Watersheds with the highest urban/residential component scores were those with large amounts of urban and residential land use. A third component was related to two herbicides (EPTC and cyanazine) used on dry beans and corn, the fourth to an herbicide (simazine) and an insecticide (carbaryl) commonly used in orchards and vineyards, and the fifth to an herbicide (DCPA). Results of this study indicate that this approach can be used to: (1) identify common mixtures of pesticides in surface waters, (2) relate these mixtures to land use and pesticide applications, and (3) indicate regions where these mixtures of pesticides are commonly found.

Acute toxicity of selected herbicides and surfactants to larvae of the midge Chironomus riparius

USGS Publications Warehouse

Buhl, Kevin J.; Faerber, Neil L.

1989-01-01

The acute toxicities of eight commercial herbicides and two surfactants to early fourth instar larvae of the midgeChironomus riparius were determined under static conditions. The formulated herbicides tested were Eradicane® (EPTC), Fargo® (triallate), Lasso® (alachlor), ME4 Brominal® (bromoxynil), Ramrod® (propachlor), Rodeo® (glyphosate), Sencor®(metribuzin), and Sutan (+)® (butylate); the two surfactants were Activator N.F.® and Ortho X-77®. In addition, technical grade alachlor, metribuzin, propachlor, and triallate were tested for comparison with the formulated herbicides. The relative toxicity of the commercial formulations, based on percent active ingredient, varied considerably. The EC50 values ranged from 1.23 mg/L for Fargo® to 5,600 mg/L for Rodeo®. Fargo®, ME4 Brominal®, and Ramrod®were moderately toxic to midge larvae; Lasso®, Sutan (+)®, and Eradicane® were slightly toxic; and Sencor® and Rodeo® were practically non-toxic. The 48-hr EC50 values of the two surfactants were nearly identical and were considered moderately toxic to midges. For two of the herbicides in which the technical grade material was tested, the inert ingredients in the formulations had a significant effect on the toxicity of the active ingredients. Fargo® was twice as toxic as technical grade triallate, whereas Sencor® was considerably less toxic than technical grade metribuzin. A comparison of the slope function values indicated that the toxic action of all the compounds occurred within a relatively narrow range. Published acute toxicity data on these compounds for other freshwater biota were tabulated and compared with our results. In general, the relative order of toxicity toC. riparius was similar to those for other freshwater invertebrates and fish. Maximum concentrations of each herbicide in bulk runoff during a projected “critical” runoff event were calculated as a percentage of the application rate lost in a given volume of runoff. A comparison between estimated maximum herbicide concentrations in runoff and results of acute tests indicated that Ramrod®, ME4 Brominal®, and Lasso® pose the greatest direct risk to midge larvae during a storm event.

Identification of a new sulfonic acid metabolite of metolachlor in soil

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.; Yockel, M.E.; Zimmerman, L.R.; Williams, T.D.

1996-01-01

An ethanesulfonic acid metabolite of metolachlor (metolachlor ESA) was identified in soil-sample extracts by negative-ion, fast-atom bombardment mass spectrometry (FAB-MS) and FAB tandem mass spectrometry (FAB-MS/MS). Production fragments from MS/MS analysis of the deprotonated molecular ion of metolachlor ESA in the soil extract can be reconciled with the structure of the synthesized standard. The elemental compositions of the (M - H)- ions of the metolachlor ESA standard and the soil-sample extracts were confirmed by high-resolution mass spectrometry. A dissipation study revealed that metolachlor ESA is formed in soil under field conditions corresponding to a decrease in the concentration of the parent herbicide, metolachlor. The identification of the sulfonated metabolite of metolachlor suggests that the glutathione conjugation pathway is a common detoxification pathway shared by chloroacetanilide herbicides.

Biodegradation and toxicity of a maize herbicide mixture: mesotrione, nicosulfuron and S-metolachlor.

PubMed

Carles, Louis; Joly, Muriel; Bonnemoy, Frédérique; Leremboure, Martin; Donnadieu, Florence; Batisson, Isabelle; Besse-Hoggan, Pascale

2018-04-21

The prediction of chemical mixture toxicity is a major concern regarding unintentional mixture of pesticides from agricultural lands treated with various such compounds. We focused our work on a mixture of three herbicides commonly applied on maize crops within a fortnight, namely mesotrione (β-triketone), nicosulfuron (sulfonylurea) and S-metolachlor (chloroacetanilide). The metabolic pathways of mesotrione and nicosulfuron were qualitatively and quantitatively determined with a bacterial strain (Bacillus megaterium Mes11). This strain was isolated from an agricultural soil and able to biotransform both these herbicides. Although these pathways were unaffected in the case of binary or ternary herbicide mixtures, kinetics of nicosulfuron disappearance and also of mesotrione and nicosulfuron metabolite formation was strongly modulated. The toxicity of the parent compounds and metabolites was evaluated for individual compounds and mixtures with the standardized Microtox® test. Synergistic interactions were evidenced for all the parent compound mixtures. Synergistic, antagonistic or additive toxicity was obtained depending on the metabolite mixture. Overall, these results emphasize the need to take into account the active ingredient and metabolites all together for the determination of environmental fate and toxicity of pesticide mixtures. Copyright © 2018 Elsevier B.V. All rights reserved.

Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa

USGS Publications Warehouse

Kalkhoff, Stephen J.; Vecchia, Aldo V.; Capel, Paul D.; Meyer, Michael T.

2012-01-01

Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model SEAWAVE-Q, which accounts for seasonal and flow-related variability. Daily estimated concentrations generated from the model were used with daily streamflow to calculate daily and yearly loads. Acetochlor, alachlor, metolachlor, and their ESA and OXA degradates were generally present in >50% of the samples collected from both sites throughout the study. Their concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. Concentrations of the ESA and OXA degradates decreased from 3 to about 23% yr-1. The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds during the study period, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed moved a greater percentage of the applied herbicides, especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage.

A High-Performance Liquid Chromatography-Based Screening Method for the Analysis of Atrazine, Alachlor, and Ten of Their Transformation Products

USGS Publications Warehouse

Schroyer, B.R.; Capel, P.D.

1996-01-01

A high-performance liquid Chromatography (HPLC) method is presented for the for the fast, quantitative analysis of the target analytes in water and in low organic-carbon, sandy soils that are known to be contaminated with the parent herbicides. Speed and ease of sample preparation was prioritized above minimizing detection limits. Soil samples were extracted using 80:20 methanol:water (volume:volume). Water samples (50 ??L) were injected directly into the HPLC without prior preparation. Method quantification limits for soil samples (10 g dry weight) and water samples ranged from 20 to 110 ng/g and from 20 to 110 ??g/L for atrazine and its transformation products and from 80 to 320 ng/g and from 80 to 320 ??g/L for alachlor and its transformation products, respectively.

Plan of study to determine the effect of changes in herbicide use on herbicide concentrations in Midwestern streams, 1989-94

USGS Publications Warehouse

Goolsby, Donald A.; Boyer, Laurie L.; Battaglin, William A.

1994-01-01

An approach was developed to determine if recent changes in the use of herbicides has affected herbicide concentrations in Midwestern streams. This approach also provides a plan to determine if the abnormally high rainfall and flooding in 1993 has an effect on nitrate concentrations in 1994 in streams that flooded in 1993. The approach involves sampling 53 stream sites, 50 of which were sampled in 1989 and 1990 as part of a reconnaissance to determine the geographic and seasonal distribution of herbicides in 10 Midwestern States. Sites will be sampled twice, once prior to application of herbicides, in March or early April, and once during the first runoff event after application of herbicides. Samples will be analyzed for 11 herbicide and 2 atrazine metabolites by gas chromatography/mass spectrometry. Samples will also be analyzed for ESA (an alachlor metabolite), two cyanazine metabolites, and nutrients. Changes to the manufacturers' label have decreased the maximum recommended application rate for atrazine on com and sorghum by about 50 percent since the 1989-90 study. Conversely, the use of other herbicides, such as cyanazine, has increased by more than 25 percent since 1989. Statistical procedures such as Wilcoxon signed rank tests for paired samples will be used to determine if the distributions of herbicide and nitrate concentrations in 1994 are different from those measured in 1989 and 1990.

Mortality and cancer incidence among alachlor manufacturing workers 1968-99.

PubMed

Acquavella, J F; Delzell, E; Cheng, H; Lynch, C F; Johnson, G

2004-08-01

Alachlor is the active ingredient in pre-emergent herbicide formulations that have been used widely on corn, soybeans, and other crops. It has been found to cause nasal, stomach, and thyroid tumours in rodent feeding studies at levels that are much higher than likely human exposures. To evaluate mortality rates from 1968 to 1999 and cancer incidence rates from 1969 to 1999 for alachlor manufacturing workers at a plant in Muscatine, Iowa. Worker mortality and cancer incidence rates were compared to corresponding rates for the Iowa state general population. Analyses addressed potential intensity and duration of exposure. For workers with any period of high alachlor exposure, mortality from all causes combined was lower than expected (42 observed deaths, SMR 64, 95% CI 46 to 86) and cancer mortality was slightly lower than expected (13 observed deaths, SMR 79, 95% CI 42 to 136). Cancer incidence for workers with potential high exposure was similar to that for Iowa residents, both overall (29 observed cases, SIR 123, 95% CI 82 to 177) and for workers exposed for five or more years and with at least 15 years since first exposure (eight observed cases, SIR 113, 95% CI 49 to 224). There were no cases of nasal, stomach, or thyroid cancer. There were no cancers of the types found in toxicology studies and no discernible relation between cancer incidence for any site and years of alachlor exposure or time since first exposure. Despite the small size of this population, the findings are important because these workers had chronic exposure potential during extended manufacturing campaigns, while use in agriculture is typically limited to a few days or weeks each year.

Net photosynthesis and respiration of sago pondweed (Potamogeton pectinatus) exposed to herbicides

USGS Publications Warehouse

Fleming, W.J.; Ailstock, M.S.; Momot, J.J.; Hughes, Jane S.; Biddinger, Gregory R.; Mones, Eugene

1995-01-01

We determined net photosynthesis and respiration rates for sago pondweed (potamogeton pectinatus) exposed to various concentrations of 11 herbicides widely used in Maryland during the past decade. Net photosynthesis and respiration were determined by measuring changes in the. oxygen content of solutions containing dilutions of technical grade herbicides. At 20-22? C and 58 umol/m2/sec of photosynthetically active radiation (PAR), oxygen production of undosed plants averaged 0.72-2.03 mg/g fresh wt/h. Respiration rates of undosed plants averaged 0.46-0.60 mg O2/g fresh wt/h. Nominal herbicide concentrations (ng/L) that reduced net photosynthesis by 5O percent (IC5O) were: metribuzin, 8; atrazine, 29; cyanazine, 32; linuron, 70; simazine, 164; and paraquat, 240. IC5O values for 2,4-D, acifluorfen, glyphosate and metolachlor exceeded the maximum test concentration of 10,000 ng/L. The IC5O value for alachlor was estimated to be between 1,000 and 10,000 ng/L. None of the herbicides tested had a significant effect on dark respiration.

Comparison of experimental methods for determination of toxicity and biodegradability of xenobiotic compounds.

PubMed

Polo, A M; Tobajas, M; Sanchis, S; Mohedano, A F; Rodríguez, J J

2011-07-01

Different methods for determining the toxicity and biodegradability of hazardous compounds evaluating their susceptibility to biological treatment were studied. Several compounds including chlorophenols and herbicides have been evaluated. Toxicity was analyzed in terms of EC50 and by a simple respirometric procedure based on the OECD Method 209 and by the Microtox® bioassay. The values of EC50 obtained from respirometry were in all the cases higher than those from the Microtox® test. The respirometric inhibition values of chlorophenols were related well with the number of chlorine atoms and their position in the aromatic ring. In general, herbicides showed lower inhibition, being alachlor the less toxic from this criterion. For determination of biodegradability an easier and faster alternative to the OECD Method 301, with a higher biomass to substrate ratio is proposed. When this test was negative, the Zahn-Wellens one was performed in order to evaluate the inherent biodegradability. In the fast test of biodegradability, 4-chlorocatechol and 4-chlorophenol showed a complete biodegradation by an unacclimated sludge upon 48 h. These results together with their low respirometric inhibition, allow concluding that these compounds could be conveniently removed in a WWTP. Alachlor, 2,4-dichlorophenol, 2,4,6-trichlorophenol and MCPA showed a partial biodegradation upon 28 days by the Zahn-Wellens inherent biodegradability test.

Organomineral Interactions and Herbicide Sorption in Brazilian Tropical and Subtropical Oxisols under No-Tillage.

PubMed

Bonfleur, Eloana J; Kookana, Rai S; Tornisielo, Valdemar L; Regitano, Jussara B

2016-05-25

We evaluated the effects of the soil organic matter (SOM) composition, distribution between soil aggregates size, and their interactions with the mineral phase on herbicide sorption (alachlor, bentazon, and imazethapyr) in tropical and subtropical Oxisols under no-till systems (NT). Using soil physical fractionation approach, sorption experiments were performed on whole soils and their aggregates. SOM chemistry was assessed by CP/MAS (13)C NMR. The lower sorption observed in tropical soils was attributed to the greater blockage of SOM sorption sites than in subtropical soils. When these sites were exposed upon physical fractionation, sorption of the three herbicides in tropical soils increased, especially for imazethapyr. High amounts of poorly crystallized sesquioxides in these soils may have contributed to masking of sorption sites, indicating that organomineral interactions may lead to blockage of sorption sites on SOM in tropical soils.

Nonpoint-source pollutant discharges of the three major tributaries to Reelfoot Lake, west Tennessee, October 1987-September 1989

USGS Publications Warehouse

Lewis, Michael E.; Garrett, Jerry W.; Hoos, Anne B.

1992-01-01

An investigation of the concentration and loads of nitrogen, phosphorus, and suspended sediment in storm runoff to Reelfoot Lake, in western Tennessee, was conducted from October 1987 through September 1989. Concentrations of selected herbicides also were defined. Reelfoot Lake, with a sur$ace area of about 15,500 acres, is the largest natural lake in Tennessee and an important recreation and fisheries resource. Previous studies showed that the lake is hypereutrophic, a condition caused by high concentrations of nutrients in water and sediments discharged from the three principal tributaries (South Reelfoot Creek, North Reelfoot Creek, and Running Slough) to the lake. Pesticides, including herbicides, have been detected in the lake?s bottom sediments. Storm runoff contributed about 87percent of the total water discharge of the three main tributaries to Reelfoot Lake. South Reelfoot Creek contributed about 4.7 tons per acre per year of suspended sediment, while North Reelfoot Creek contributed about 1.9 tons per acre per year. Running Slough contributed only about 0.31 ton per acre per year of suspended sediment. Most of the suspended sediment was transported by storm runoff between October and March. About 80 percent of the annual streamflow of the three tributaries occurs during these months. The North Reelfoot Creek basin contributed 8.2 pounds per acre per year of total nitrogen and 2.4 pounds per acre per year of total phosphorus. South Reelfoot Creek basin contributed about 6.5 and 1.3 pounds per acre per year of total nitrogen and phosphorus, respectively, while Running Slough basin contributions were 3.4 and 0.86 pounds per acre per year, respectively. The differences in nutrient yields appear to result from more row-crop agriculture and the relatively steeply sloping agricultural land in the North Reelfoot Creek basin. Ninety-one percent of the total nitrogen load and 95 percent of the total phosphorus load in the three streams was transported by storm runof/ Significant diflerences in the mean concentrations of nutrients in runoff were defined between the active agricultural months (April through September) and the inactive months (October through March). Storm-runofS samples were analyzed for II selected triazine herbicides. Alachlor and atrazine were the most commonly detected herbicides. Thirty-two percent of the samples contained detectable levels of alachlor and 93 percent of the samples contained detectable levels of atrazine. Ninety percent of the samples collected during the active agricultural months contained detectable leveki of alachlor and all 29 samples contained detectable levels of atrazine. Sixteen samples exceeded lifetime health-advisory levels for atrazine in drinking water (3 micrograms per liter); two samples collected from the April IS, 1988, storm at North Reelfoot Creek and South Reelfoot Creek contained 42 and 57 micrograms per liter of atrazine, respectively. Concentrations of the other nine triazine herbicides were generally less than the level of detection (0.1 microgram per liter).

Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa.

PubMed

Kalkhoff, Stephen J; Vecchia, Aldo V; Capel, Paul D; Meyer, Michael T

2012-01-01

Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model SEAWAVE-Q, which accounts for seasonal and flow-related variability. Daily estimated concentrations generated from the model were used with daily streamflow to calculate daily and yearly loads. Acetochlor, alachlor, metolachlor, and their ESA and OXA degradates were generally present in >50% of the samples collected from both sites throughout the study. Their concentrations generally decreased from 1996 through 2006, although the rate of decrease was slower after 2001. Concentrations of the ESA and OXA degradates decreased from 3 to about 23% yr. The concentration trend was related to the decreasing use of these compounds during the study period. Decreasing concentrations and constant runoff resulted in an average reduction of 10 to >3000 kg per year of alachlor and metolachlor ESA and OXA degradates being transported out of the Iowa River watershed. Transport of acetochlor and metolachlor parent compounds and their degradates from the Iowa River watershed ranged from <1% to about 6% of the annual application. These trends were related to the decreasing use of these compounds during the study period, but the year-to-year variability cannot explain changes in loads based on herbicide use alone. The trends were also affected by the timing and amount of precipitation. As expected, increased amounts of water moving through the watershed moved a greater percentage of the applied herbicides, especially the relatively soluble degradates, from the soils into the rivers through surface runoff, shallow groundwater inflow, and subsurface drainage. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Analytical Confirmation of Various Herbicides in Drinking Water Resources in Sugarcane Production Regions of Guangxi, China.

PubMed

Li, Honghong; Feng, Yujie; Li, Xuesheng; Zeng, Dongqiang

2018-06-01

This work investigated drinking water contamination by 11 commonly used herbicides in sugarcane production areas in Guangxi, China. The work developed an analytical method for determination of these herbicides in environmental waters. This work studied herbicide residues in drinking water in Guangxi, China. The maximum residues and percent of detects were: (0.091 µg/L, 29.2%, atrazine), (0.018 µg/L, 8.3%, ametryne), (0.188 µg/L, 8.3%, aetolaehlor), (0.139 µg/L, 4%, simazine), (0.585 µg/L, 62.5%, atrazine), (0.311 µg/L, 33.3%, acetochlor), (0.341 µg/L, 58.3%, ametryne), (1.312 µg/L, 29.2%, metolachlor), (0.088 µg/L, 4.2%, alachlor), (0.127 µg/L, 14.3%, atrazine), and (0.453 µg/L, 7.1%, metolachlor), respectively. The results demonstrated that agricultural herbicides were detected in all water samples, including tap, surface and groundwater samples. Since the residues are generally below the safe limits established by the government authorities, the monitored 11 herbicides do not significantly affect the quality of the human environment. This work will provide scientific understanding of pesticide residues in drinking water standards in terms of its consistency with precautionary human health and environmental safety.

Atmospheric influence on the distribution of organic pollutants in the Guadalquivir River estuary, SW Spain.

PubMed

Fernández-Gómez, Cristal; López-López, José Antonio; Matamoros, Victor; Díez, Sergi; García-Vargas, Manuel; Moreno, Carlos

2013-04-01

In the lower Guadalquivir river basin, a system stressed by a wide variety of anthropogenic activities, eight pesticides (four triazines, two chloroacetanilide herbicides, one organochlorine, and one organophosphorus insecticide); and four emerging pollutants (two personal care products, one organophosphorous flame retardant, and one xanthine alkaloid) were analyzed in river water during a 2-year monitoring program, and after rain episodes. Samples were extracted using the solid phase extraction (SPE) technique prior to determination of compounds using gas chromatograph coupled to a mass spectrometer detector. Except for caffeine, recoveries were mostly above 80 %, while limits of detection and quantification were in the low nanograms per liter level (except for dimethoate). Terbuthylazine, simazine (triazine herbicides), and dimethoate (organophosphorus insecticide), present in agrochemicals, were predominant in the river water, although concentrations were below the quality standards established by the EU Water-Framework-Directive. A general trend to increase concentration was observed after rain events, in particular for pesticides, possibly as a consequence of surface runoff.

The occurrence and transport of agricultural pesticides in the Tuttle Creek lake-stream system, Kansas and Nebraska

USGS Publications Warehouse

Bevans, Hugh E.; Fromm, Carla Hyde; Watkins, Sharon A.

1995-01-01

Median monthly atrazine concentrations detected in surface-water samples from the Big Blue River basin (1977-86) exceeded the U.S. Environmental Protection Agency health-advisory level (3.0 micrograms per liter) during May through September. Herbicide loads transported from the basin in 1986, expressed in tons and in percentage of amount applied, were alachlor (1.2 tons, 0.23 percent), atrazine (19 tons, 2.2 percent), and metolachlor (2.2 tons, 2.7 percent).

Occurrence and distribution of pesticides in streams of the Eastern Iowa Basins, 1996-98

USGS Publications Warehouse

Schnoebelen, Douglas J.; Kalkhoff, Stephen J.; Becher, Kent D.

2001-01-01

Occurrence of pesticide compounds varied by landform region. The triazine herbicides, atrazine and cyanazine and their degradates were present in significantly greater concentrations in the Southern Iowa Drift Plain (predominantly loess soils) than either the Des Moines Lobe or the Iowan Surface (predominantly till soils). Less atrazine and cyanazine are applied to till soils because of pH and organic carbon content. Alachlor, metolachlor, and acetochlor have often been used to offset triazine pesticide reductions in area with till soils.

Distribution of agrochemicals in the lower Mississippi River and its tributaries

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.

1990-01-01

The Mississippi River and its tributaries drain extensive agricultural regions of the Mid-Continental United States. Millions of pounds of herbicides are applied annually in these areas to improve crop yields. Many of these compounds are transported into the river from point and nonpoint sources, and eventually are discharged into the Gulf of Mexico. Studies being conducted by the U.S. Geological Survey along the lower Mississippi River and its major tributaries, representing a 2000 km river reach, have confirmed that several triazine and acetanilide herbicides and their degradation products are ubiquitous in this riverine system. These compounds include atrazine and its degradation products desethyl and desisopropylatrazine, cyanazine, simazine, metolachlor, and alachlor and its degradation products 2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6-diethylacetanilide and 2,6-diethylaniline. Loads of these compounds were determined at 16 different sampling stations. Stream-load calculations provided information concerning (a) conservative or nonconservative behavior of herbicides; (b) point sources or nonpoint sources; (c) validation of sampling techniques; and (d) transport past each sampling station.

Pesticide distributions in surface water: The distribution of pesticide concentrations at two study sites points to herbicides that may affect management of public water supplies

USGS Publications Warehouse

Stamer, J.K.; Wieczorek, M.E.

1996-01-01

Distributions of concentrations of 46 pesticides were documented from May 1992 through March 1994 for Maple Creek near Nickerson, Neb., and Platte River at Louisville, Neb. As their source of public water supplies, Lincoln and the western part of Omaha withdraw groundwater from the adjacent alluvium near the Platte River site, which is hydraulically connected to the Platte River. Organonitrogen herbicides dominated the pesticide distributions at each site. Variations in the distributions of pesticides at the two sites partly reflect differences in land use and land management practices. Diazinon, an insecticide used in urban areas, was commonly detected at the Platte River site but not at the Maple Creek site. Of the 46 pesticides analyzed at the Platte River site, the herbicides atrazine and alachlor were more likely to exceed their respective maximum contaminant levels of 3.0 and 2.0 pg/L; cyanazine was more likely to exceed the health advisory level of 1.0 ??g/L.

BOREAS TGB-7 Rainwater Herbicide and Organochlorine Concentration Data

NASA Technical Reports Server (NTRS)

Waite, Don; Conrad, Sara K. (Editor); Hall, Forrest G. (Editor)

2000-01-01

The BOREAS TGB-7 team measured the concentration and flux of several agricultural pesticides in air and rainwater samples in order to determine the associated yearly deposition rates. This data set contains information on the rainwater concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files.

Distribution of major herbicides in ground water of the United States

USGS Publications Warehouse

Barbash, Jack E.; Thelin, Gail P.; Kolpin, Dana W.; Gilliom, Robert J.

1999-01-01

Frequencies of detection at or above 0.01 microgram per liter in shallow ground water beneath agricultural areas during the NAWQA study were significantly correlated with agricultural use in those areas for atrazine, cyanazine, alachlor, and metolachlor (P<0.05; Spearman rank correlations), but not for simazine (P>0.05). In urban areas, overall frequencies of detection of these five herbicides in shallow ground water were positively correlated with their total nonagricultural use nationwide (P=0.026; simple linear correlation). Multivariate statistical analysis indicated that frequencies of detection in shallow ground water beneath agricultural areas were positively correlated with half-lives for transformation in aerobic soil and agricultural use of the compounds (P≤0.0001 for both parameters). Although frequencies of detection were not significantly correlated with their subsurface mobility (Koc; P=0.19) or the median well depths of the sampled networks (P=0.72), the range of Koc values among the five herbicides and the range of well depths were limited.

Herbicide micropollutants in surface, ground and drinking waters within and near the area of Zagreb, Croatia.

PubMed

Fingler, Sanja; Mendaš, G; Dvoršćak, M; Stipičević, S; Vasilić, Ž; Drevenkar, V

2017-04-01

The frequency and mass concentrations of 13 herbicide micropollutants (triazines, phenylureas, chloroacetanilides and trifluralin) were investigated during 2014 in surface, ground and drinking waters in the area of the city of Zagreb and its suburbs. Herbicide compounds were accumulated from water by solid-phase extraction using either octadecylsilica or styrene-divinylbenzene sorbent cartridges and analysed either by high-performance liquid chromatography with UV-diode array detector or gas chromatography with mass spectrometric detection. Atrazine was the most frequently detected herbicide in drinking (84 % of samples) and ground (61 % of samples) waters in mass concentrations of 5 to 68 ng L -1 . It was followed by metolachlor and terbuthylazine, the former being detected in 54 % of drinking (up to 15 ng L -1 ) and 23 % of ground (up to 100 ng L -1 ) waters, and the latter in 45 % of drinking (up to 20 ng L -1 ) and 26 % of ground (up to 25 ng L -1 ) water samples. Acetochlor was the fourth most abundant herbicide in drinking waters, detected in 32 % of samples. Its mass concentrations of 107 to 117 ng L -1 in three tap water samples were the highest of all herbicides measured in the drinking waters. The most frequently (62 % of samples) and highly (up to 887 ng L -1 ) detected herbicide in surface waters was metolachlor, followed by terbuthylazine detected in 49 % of samples in mass concentrations of up to 690 ng L -1 , and atrazine detected in 30 % of samples in mass concentrations of up to 18 ng L -1 . The seasonal variations in herbicide concentrations in surface waters were observed for terbuthylazine, metolachlor, acetochlor, chlortoluron and isoproturon with the highest concentrations measured from April to August.

Agricultural chemicals in near-surface aquifers in the mid-continental United States, 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolpin, D.W.; Burkart, M.R.

The occurrence and distribution of selected herbicides, atrazine metabolites, and nitrate were determined for unconsolidated and bedrock aquifers within 50 feet of land surface (near-surface) in the corn and soybean producing region of the mid-continental US. At least one herbicide or atrazine metabolite was detected (reporting limit, 0.05 micrograms per liter) in 24 percent of 579 water samples collected during the spring and summer of 1991. No herbicide exceeded maximum contaminant levels or health advisories. Most frequently detected was desethylatrazine (18.1 percent) followed by atrazine (17.4 percent), deisopropylatrazine (5.7 percent) and prometon (5.0 percent). Metolachlor, alachlor, metribuzin, simazine, and cyanazinemore » were found in fewer than 3 percent of the samples. Excess nitrate (more than 3.0 mg/L) was found in 29 percent of the samples; 6 percent exceeded 10 mg/L. Few herbicide detections or excess nitrate concentrations occurred in the eastern part of the study region even though this area had an intense use of herbicides and nitrogen-fertilizer. The source of prometon, the second most frequently detected herbicide, may be associated with nonagricultural land use such as golf courses and residential areas. Significant seasonal differences between the spring and summer sampling periods were found in herbicide detections, but not in excess nitrate. The frequency of herbicide detections and excess nitrate were greater in near-surface unconsolidated aquifers than found in near-surface bedrock aquifers. Depth to the top of the aquifer was inversely related to the frequency of both herbicide detection and excess nitrate. The proximity of sampling sites to streams affected the frequency of herbicide detection.« less

Response of sago pondweed, a submerged aquatic macrophyte, to herbicides in three laboratory culture systems

USGS Publications Warehouse

Fleming, W.J.; Ailstock, M.S.; Momot, J.J.; Norman, C.M.; Gorsuch, Joseph W.; Lower, William R.; Wang, Wun-cheng; Lewis, M.A.

1991-01-01

The phytotoxicity of atrazine, paraquat, glyphosate, and alachlor to sago pondweed (Potamogeton pectinatus), a submerged aquatic macrophyte, was tested under three types of laboratory culture conditions. In each case, tests were conducted in static systems, the test period was four weeks, and herbicide exposure was chronic, resulting from a single addition of herbicide to the test vessels at the beginning of the test period. The three sets of test conditions employed were(1) axenic cultures in 125-mL flasks containing a nutrient media and sucrose; (2) a microcosm system employing 18.9-L buckets containing a sand, shell, and peat substrate; and (3) an algae-free system employing O.95-L jars containing reconstituted freshwater and a nutrient agar substrate. The primary variable measured was biomass production. Plants grew well in all three test systems, with biomass of untreated plants increasing by a factor of about 5 to 6.5 during the four-week test period. Biomass production in response to herbicide exposure differed significantly among culture systems, which demonstrates the need for a standardized testing protocol for evaluating the effects of toxics on submerged aquatic plants.

BOREAS TGB-7 Dry Deposition Herbicide and Organochlorine Flux Data

NASA Technical Reports Server (NTRS)

Waite, Don; Conrad, Sara K. (Editor); Hall, Forrest G. (Editor)

2000-01-01

The BOREAS TGB-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the dry deposition flux of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files.

Screening and selection of most potent diazotrophic cyanobacterial isolate exhibiting natural tolerance to rice field herbicides for exploitation as biofertilizer.

PubMed

Singh, Surendra; Datta, Pallavi

2006-01-01

Periodic applications of heavy dosages of herbicides in modern rice-agriculture are a necessary evil for obtaining high crop productivity. Such herbicides are not only detrimental to weeds but biofertilizer strains of diazotrophic cyanobacteria also. It is therefore, essential to screen and select such biofertilizer strains of diazotrophic cyanobacteria exhibiting natural tolerance to common rice-field herbicides that can be further improved by mutational techniques to make biofertilizer technology a viable one. Therefore, efforts have been made to screen five dominant diazotrophic cyanobacterial forms e.g. filamentous heterocystous Nostoc punctiforme , Nostoc calcicola , Anabaena variabilis and unicellular Gloeocapsa sp. and Aphanocapsa sp. along with standard laboratory strain Nostoc muscorum ISU against increasing concentrations (0-100 mg l(-1) of four commercial grade common rice-field herbicides i.e. Arozin, Butachlor, Alachlor and 2,4-D under diazotrophic growth conditions. The lethal and IGC(50) concentrations for all four herbicides tested were found highest for A. variabilis as compared to other test cyanobacteria. The lowest reduction in chlorophyll a content, photosynthetic oxygen evolution, and N(2)-fixation was found in A. variabilis as compared to other rice field isolates and standard laboratory strain N. muscorum ISU. On the basis of prolong survival potential and lowest reductions in vital metabolic activities tested at IGC(50) concentration of four herbicides, it is concluded that A. variabilis is the most potent and promising cyanobacterial isolate as compared with other forms. This could be further improved by mutational techniques for exploitation as most potential and viable biofertilizer strain.

Comparison of two screening bioassays, based on the frog sciatic nerve and yeast cells, for the assessment of herbicide toxicity.

PubMed

Papaefthimiou, Chrisovalantis; Cabral, Maria de Guadalupe; Mixailidou, Christina; Viegas, Cristina A; Sá-Correia, Isabel; Theophilidis, George

2004-05-01

Two different test systems, one based on the isolated sciatic nerve of an amphibian and the other on a microbial eukaryote, were used for the assessment of herbicide toxicity. More specifically, we determined the deleterious effects of increasing concentrations of herbicides of different chemical classes (phenoxyacetic acids, triazines, and acetamides), and of 2,4-dichlorophenol (2,4-DCP), a degradation product of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), on electrophysiological parameters and the vitality of the axons of the isolated sciatic nerve of the frog (Rana ridibunda) and on the growth curve of the yeast Saccharomyces cerevisiae based on microtiter plate susceptibility assays. The no-observed-effect-concentration (NOEC), defined as the maximum concentration of the tested compound that has no effect on these biological parameters, was estimated. In spite of the different methodological approaches and biological systems compared, the NOEC values were identical and correlated with the lipophilicity of the tested compounds. The relative toxicity established here, 2,4-DCP > alachlor, metolachlor > metribuzin > 2,4-D, 2-methyl-4-chlorophenoxyacetic acid (MCPA), correlates with the toxicity indexes reported in the literature for freshwater organisms. Based on these results, we suggest that the relatively simple, rapid, and low-cost test systems examined here may be of interest as alternative or complementary tests for toxicological assessment of herbicides.

Agricultural chemicals in alluvial aquifers in Missouri after the 1993 flood

USGS Publications Warehouse

Heimann, D.C.; Richards, J.M.; Wilkison, D.H.

1997-01-01

Intense rains produced flooding during the spring and summer of 1993 over much of the midwestern USA including many agricultural areas of Missouri. Because of potential contamination from floodwater, an investigation was conducted to determine the changes in concentrations of agricultural chemicals in water samples from alluvial wells in Missouri after the flood. Water samples from 80 alluvial wells with historical data were collected in March, July, and November 1994, and analyzed for dissolved herbicides, herbicide metabolites, and nitrate (NO3). There were no statistically significant differences in the distribution of alachlor ((2,chloro-2'-6'-diethyl-N-[methoxymethyl]acetanilide), atrazine (2-chloro- 4-ethylamino-6-isopropylamino-1, 3, 5 triazine), and nitrate concentrations between pre- and postflood samples (?? = 0.05). The detection frequency of alachlor and atrazine in postflood samples was generally lower than the frequency in preflood samples. Analyses of agricultural chemicals in water samples from an intensely sampled well field indicate significant differences between the distribution of dissolved P concentrations in pre- and postflood samples (?? = 0.05). However, no significant differences were detected between the pre- and postflood distributions of NO3 or ammonia concentrations. Because of the numerous sources of temporal variability and the relatively short record of water-quality data for the study wells, a cause-and-effect relation between changes in agricultural chemical concentrations and a single factor of the 1993 flood is difficult to determine. Based on the results of this study, the 1993 flood did not cause widespread or long-term significant changes in concentrations of agricultural chemicals in water from alluvial aquifers in Missouri.

Pesticides in Streams in Central Nebraska

USGS Publications Warehouse

Stamer, J.K.; Wieczorek, Michael

1995-01-01

Contamination of surface and ground water from non-point sources is a national issue. Examples of nonpoint-source contaminants from agricultural activities are pesticides, which include fungicides, herbicides, and insecticides; sediment; nutrients (nitrogen and phosphorus); and fecal bacteria. Of these contaminants, pesticides receive the most attention because of the potential toxicity to aquatic life and to humans. Most farmers use pesticides to increase crop yields and values. Herbicides prevent or inhibit the growth of weeds that compete for nutrients and moisture needed by the crops. Herbicides are applied before, during, or following planting. In addition to agricultural use, herbicides are used in urban areas, often in larger rates of application, for weed control such as among rights-of-way. Alachlor, atrazine, cyanazine, and metolachlor, which are referred to as organonitrogen herbicides, were the four most commonly applied herbicides (1991) in the Central Nebraska Basins (CNB). These herbicides are used for corn, sorghum, and soybean production. Atrazine was the most extensively applied pesticide (1991) in central Nebraska. Insecticides are used to protect the crop seeds in storage prior to planting and also to protect the plants from destruction once the seeds have germinated. Like herbicides, insecticides are also used in urban areas to protect lawns, trees, and ornamentals. Many of the 46 pesticides shown in the table have either a Maximum Contaminant Level (MCL) of Health Advisory Level (HAL) established by the U.S. Environmental Protection Agency (USEPA) for public water supplies. The purposes of this Fact Sheet are to (1) to provide water-utility managers, water-resources planners and managers, and State regulators an improved understanding of the distributions of concentrations of pesticides in streams and their relation to respective drinking-water regulations or criteria, and (2) to describe concentrations of pesticides in streams draining a selected small agricultural basin and a large agricultural area.

Extraction of acetanilides in rice using ionic liquid-based matrix solid phase dispersion-solvent flotation.

PubMed

Zhang, Liyuan; Wang, Changyuan; Li, Zuotong; Zhao, Changjiang; Zhang, Hanqi; Zhang, Dongjie

2018-04-15

Ionic liquid-based matrix solid phase dispersion-solvent flotation coupled with high performance liquid chromatography was developed for the determination of the acetanilide herbicides, including metazachlor, propanil, alachlor, propisochlor, pretilachlor, and butachlor in rice samples. Some experimental parameters, including the type of dispersant, the mass ratio of dispersant to sample, pH of sample solution, the type of extraction solvent, the type of ionic liquid, flotation time, and flow rate of N 2 were optimized. The average recoveries of the acetanilide herbicides at spiked concentrations of 50, 125, and 250 µg/kg ranged from 89.4% to 108.7%, and relative standard deviations were equal to or lower than 7.1%, the limits of quantification were in the range of 38.0 to 84.7 µg/kg. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrence of Organic Contaminants in Lower Reaches of River Ganges, India

NASA Astrophysics Data System (ADS)

Dutta Gupta, S.; Bhattacharya, A.; Mukherjee, A.; Bhattacharya, J.

2016-12-01

The Gangetic plain of eastern India has been long known as the "bread basket" of the Indian subcontinent. However, indiscriminate use of pesticides in the agricultural fields is to increase crop production. These resulted to increased vulnerability of pesticide pollution of the hydrological systems of the area, potentially exposing to significant human health consequences. Our present study delineate pesticides occurrence in lower Ganges in West Bengal. The major organic contaminants regularly detected in the studied reaches of the Ganges belong to wide range of herbicides and insecticides, which especially include organochlorides and organophosphates such as Aldrin, Alachlor, Lindane, Malathion, Chlorpyrifos and Methyl parathion. Results show Alachlor and Malathion were the most abundant organic contaminant in the river. Among the other pesticides, one of the most venomous substances, Malathion has been noticed from the last year insecticide screening study. The mean concentration of river water Malathion was found to be 5 times higher than the maximum concentration limit (MCL). Presence of Malathion or its derivative Malaoxon in river water is suspected to be caused by agricultural run-off and it showed a good correlation with river water chlorine concentrations.

Hypospadias and residential proximity to pesticide applications.

PubMed

Carmichael, Suzan L; Yang, Wei; Roberts, Eric M; Kegley, Susan E; Wolff, Craig; Guo, Liang; Lammer, Edward J; English, Paul; Shaw, Gary M

2013-11-01

Experimental evidence suggests pesticides may be associated with hypospadias. Examine the association of hypospadias with residential proximity to commercial agricultural pesticide applications. The study population included male infants born from 1991 to 2004 to mothers residing in 8 California counties. Cases (n = 690) were ascertained by the California Birth Defects Monitoring Program; controls were selected randomly from the birth population (n = 2195). We determined early pregnancy exposure to pesticide applications within a 500-m radius of mother's residential address, using detailed data on applications and land use. Associations with exposures to physicochemical groups of pesticides and specific chemicals were assessed using logistic regression adjusted for maternal race or ethnicity and age and infant birth year. Forty-one percent of cases and controls were classified as exposed to 57 chemical groups and 292 chemicals. Despite >500 statistical comparisons, there were few elevated odds ratios with confidence intervals that excluded 1 for chemical groups or specific chemicals. Those that did were for monochlorophenoxy acid or ester herbicides; the insecticides aldicarb, dimethoate, phorate, and petroleum oils; and adjuvant polyoxyethylene sorbitol among all cases; 2,6-dinitroaniline herbicides, the herbicide oxyfluorfen, and the fungicide copper sulfate among mild cases; and chloroacetanilide herbicides, polyalkyloxy compounds used as adjuvants, the insecticides aldicarb and acephate, and the adjuvant nonyl-phenoxy-poly(ethylene oxy)ethanol among moderate and severe cases. Odds ratios ranged from 1.9 to 2.9. Most pesticides were not associated with elevated hypospadias risk. For the few that were associated, results should be interpreted with caution until replicated in other study populations.

Hypospadias and Residential Proximity to Pesticide Applications

PubMed Central

Yang, Wei; Roberts, Eric M.; Kegley, Susan E.; Wolff, Craig; Guo, Liang; Lammer, Edward J.; English, Paul; Shaw, Gary M.

2013-01-01

BACKGROUND: Experimental evidence suggests pesticides may be associated with hypospadias. OBJECTIVE: Examine the association of hypospadias with residential proximity to commercial agricultural pesticide applications. METHODS: The study population included male infants born from 1991 to 2004 to mothers residing in 8 California counties. Cases (n = 690) were ascertained by the California Birth Defects Monitoring Program; controls were selected randomly from the birth population (n = 2195). We determined early pregnancy exposure to pesticide applications within a 500-m radius of mother’s residential address, using detailed data on applications and land use. Associations with exposures to physicochemical groups of pesticides and specific chemicals were assessed using logistic regression adjusted for maternal race or ethnicity and age and infant birth year. RESULTS: Forty-one percent of cases and controls were classified as exposed to 57 chemical groups and 292 chemicals. Despite >500 statistical comparisons, there were few elevated odds ratios with confidence intervals that excluded 1 for chemical groups or specific chemicals. Those that did were for monochlorophenoxy acid or ester herbicides; the insecticides aldicarb, dimethoate, phorate, and petroleum oils; and adjuvant polyoxyethylene sorbitol among all cases; 2,6-dinitroaniline herbicides, the herbicide oxyfluorfen, and the fungicide copper sulfate among mild cases; and chloroacetanilide herbicides, polyalkyloxy compounds used as adjuvants, the insecticides aldicarb and acephate, and the adjuvant nonyl-phenoxy-poly(ethylene oxy)ethanol among moderate and severe cases. Odds ratios ranged from 1.9 to 2.9. CONCLUSIONS: Most pesticides were not associated with elevated hypospadias risk. For the few that were associated, results should be interpreted with caution until replicated in other study populations. PMID:24167181

BOREAS TGB-7 Ambient Air Herbicide and Organochlorine Concentration Data

NASA Technical Reports Server (NTRS)

Waite, Don; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the ambient air concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

Determination of trace levels of herbicides and their degradation products in surface and ground waters by gas chromatography/ion-trap mass spectrometry

USGS Publications Warehouse

Pereira, W.E.; Rostad, C.E.; Leiker, T.J.

1990-01-01

A rapid, specific and highly sensitive method is described for the determination of several commonly used herbicides and their degradation products in surface and ground waters by using gas chromatography/ion-trap mass spectrometry. The compounds included atrazine, and its degradation products desethylatrazine and desisopropylatrazine; Simazine; Cyanazine; Metolachlor; and alachlor and its degradation products, 2-chloro-2', 6'-diethylacetanilide, 2-hydroxy-2', 6'-diethylacetanilide and 2,6-diethylaniline. The method was applied to surface-water samples collected from 16 different stations along the lower Mississippi River and its major tributaries, and ground-water samples beneath a cornfield in central Nebraska. Average recovery of a surrogate herbicide, terbuthylazine, was greater than 99%. Recoveries of the compounds of interest from river water spiked at environmental levels are also presented. Full-scan mass spectra of these compounds were obtained on 1 ng or less of analyte. Data were collected in the full-scan acquisition mode. Quantitation was based on a single characteristic ion for each compound. The detection limit was 60 pg with a signal-to-noise ratio of greater than 10:1.

Herbicide and degradate flux in the Yazoo River Basin

USGS Publications Warehouse

Coupe, R.H.; Welch, H.L.; Pell, A.B.; Thurman, E.M.

2005-01-01

During 1996-1997, water samples were collected from five sites in the Yazoo River Basin and analysed for 14 herbicides and nine degradates. These included acetochlor, alachlor, atrazine, cyanazine, fluometuron, metolachlor, metribuzin, molinate, norflurazon, prometryn, propanil, propazine, simazine, trifluralin, three degradates of fluometuron, two degradates of atrazine, one degradate of cyanazine, norflurazon, prometryn, and propanil. Fluxes generally were higher in 1997 than in 1996 due to a greater rainfall in 1997 than 1996. Fluxes were much larger from streams in the alluvial plain (an area of very productive farmland) than from the Skuna River in the bluff hills (an area of small farms, pasture, and forest). Adding the flux of the atrazine degradates to the atrazine flux increased the total atrazine flux by an average of 14.5%. The fluometuron degradates added about 10% to the total fluometuron flux, and adding the norflurazon degradate flux to the norflurazon flux increased the flux by 82% in 1996 and by 171% in 1997. ?? 2005 Taylor & Francis.

Adsorption of cellular peptides of Microcystis aeruginosa and two herbicides onto activated carbon: effect of surface charge and interactions.

PubMed

Hnatukova, Petra; Kopecka, Ivana; Pivokonsky, Martin

2011-05-01

In this research, the adsorption of two herbicides, alachlor (ALA) and terbuthylazine (TBA), on granular activated carbon (GAC) in the presence of well-characterized peptide fraction of cellular organic matter (COM) produced by cyanobacterium Microcystis aeruginosa was studied. Two commercially available GACs were characterized using nitrogen gas adsorption and surface charge titrations. The COM peptides of molecular weight (MW) < 10 kDa were isolated and characterized using MW fractionation technique and high-performance size exclusion chromatography (HPSEC). The effect of surface charge on the adsorption of COM peptides was studied by means of equilibrium adsorption experiments at pH 5 and pH 8.5. Electrostatic interactions and hydrogen bonding proved to be important mechanisms of COM peptides adsorption. The adsorption of ALA and TBA on granular activated carbon preloaded with COM peptides was influenced by solution pH. The reduction in adsorption was significantly greater at pH 5 compared to pH 8.5, which corresponded to the increased adsorption of COM peptides at pH 5. The majority of the competition between COM peptides and both herbicides was attributed to low molecular weight COM peptides with MW of 700, 900, 1300 and 1700 Da. Copyright © 2011 Elsevier Ltd. All rights reserved.

Occurrence of sulfonylurea, sulfonamide, imidazolinone, and other herbicides in rivers, reservoirs and ground water in the Midwestern United States, 1998

USGS Publications Warehouse

Battaglin, W.A.; Furlong, E.T.; Burkhardt, M.R.; Peter, C.J.

2000-01-01

Sulfonylurea (SU), sulfonamide (SA), and imidazolinone (IMI) herbicides are relatively new classes of chemical compounds that function by inhibiting the action of a plant enzyme, stopping plant growth, and eventually killing the plant. These compounds generally have low mammalian toxicity, but plants demonstrate a wide range in sensitivity to SUs, SAs, and IMIs with over a 10000-fold difference in observed toxicity levels for some compounds. SUs, SAs, and IMIs are applied either pre- or post-emergence to crops commonly at 1/50th or less of the rate of other herbicides. Little is known about their occurrence, fate, or transport in surface water or ground water in the USA. To obtain information on the occurrence of SU, SA, and IMI herbicides in the Midwestern United States, 212 water samples were collected from 75 surface-water and 25 ground-water sites in 1998. These samples were analyzed for 16 SU, SA and IMI herbicides by USGS Methods Research and Development Program staff using high-performance liquid chromatography/mass spectrometry. Samples were also analyzed for 47 pesticides or pesticide degradation products. At least one of the 16 SUs, SAs or IMIs was detected above the method reporting limit (MRL) of 0.01 ??g/l in 83% of 130 stream samples. Imazethapyr was detected most frequently (71% of samples) followed by flumetsulam (63% of samples) and nicosulfuron (52% of samples). The sum of SU, SA and IMI concentrations exceeded 0.5 ??g/l in less than 10% of stream samples. Acetochlor, alachlor, atrazine, cyanazine and metolachlor were all detected in 90% or more of 129 stream samples. The sum of the concentration of these five herbicides exceeded 50 ??g/l in approximately 10% of stream samples. At least one SU, SA, or IMI herbicide was detected above the MRL in 24% of 25 ground-water samples and 86% of seven reservoir samples. Copyright (C) 2000 Elsevier Science B.V.

The Reaction Mechanism and Kinetics for the Reaction of OH Radicals with Atmospheric Metolachlor

NASA Astrophysics Data System (ADS)

Chen, Chao; Zhou, Qin; Zheng, Jian; Jin, Xinhui; Ma, Wanyong; Zhou, Jianhua

2018-07-01

Metolachlor [2-chloro- N-(2-ethyl-6-methylphenyl)- N-(2-methoxy-1-methylethyl)acetamide], has been used as a chloroacetanilide herbicide to control annual grass weeds and broadleaf weeds in corn, cotton, peanuts, soybeans and beans. In this paper, aRS-metolachlor has been used as a model to investigate the reaction of OH radicals with atmospheric metolachlor. The reaction mechanism was obtained at the MPWB1K/6-311 + g(3 df,2 p)//MPWB1K/6-31 + g( d, p) level of theory and the rate constants were deduced over the temperature range of 180-370 K using canonical variational transition state (CVT) theory with the small curvature tunneling (SCT) method. The atmospheric lifetime of aRS-metolachlor determined by OH radicals is about 3.97 h, which indicates that it can be degradaded in the gas phase easily and doesn't have the potential for long-range transport.

Herbicide Transformation

PubMed Central

Lanzilotta, R. P.; Pramer, David

1970-01-01

Replacement cultures liberated 3,4-dichloroaniline (DCA) from 3,4-dichloropropionanilide (propanil). The kinetics of the conversion suggest a requirement for de novo enzyme synthesis, but the system was not influenced by chloramphenicol or puromycin. Enzyme activity was detected when acetanilide (Km = 0.195 mm) was used to replace propanil as substrate. Fungal acylamidase (E.C. 3.5.1., an aryl acylamine amidohydrolase) was concentrated by salt precipitation and characterized. The Fusarium solani acylamidase exhibited an optimum at pH 7.5 to 9.0 and was inactivated in 10 min at 50 C. The enzyme was not sensitive to methyl-carbamate or organophosphate insecticides, but the herbicide, Ramrod (N-isopropyl-2-chloroacetanilide), acted as a competitive inhibitor of acetanilide hydrolysis (Ki = 0.167 mm). Hydrolysis rates were decreased by various para substitutions of acetanilide. Chloro substitution in the acyl moiety of acetanilide also reduced the rate of hydrolysis. 3,4-Dichloroacetanilide was less susceptible to enzyme action than acetanilide, but 3,4-dichloropropionanilide was hydrolyzed much more rapidly than propionanilide. The fungal acylamidase was highly specific for N-acetylarylamines. It did not catalyze hydrolysis of formanilide, butyranilide, dicryl, Karsil, fenuron, monuron, or isopropyl-N-phenylcarbamate. It appears to differ from acylamidases that have been isolated from rice, rat liver, chick kidney, and Neurospora. PMID:5437306

Herbicide concentrations in and loads transported by the Conestoga River and Pequea Creek, Lancaster County, Pennsylvania, 1992-95

USGS Publications Warehouse

Reed, Lloyd A.; Koerkle, Edward H.; Takita, Charles S.

1997-01-01

Water samples were collected from four streams in Lancaster County from 1992 through 1995 and analyzed for selected herbicides. Samples were collected from the Little Conestoga Creek near Churchtown, Mill Creek (a tributary to the Conestoga River) at Elshelman Mill Road near Lyndon, the Conestoga River at Conestoga, and Pequea Creek at Martic Forge. Most samples were collected from stormflow that occurred during the growing season. Samples were analyzed for alachlor, aldrin, atrazine, chlordane, cyanazine, dieldrin, malathion, metolachlor, propazine, simazine, and toxaphene. Most samples had detectable concentrations of alachlor, atrazine, metolachlor, and simazine, and the loads of these constituents that were transported during each of the 4 years were computed.Of the samples collected from each of the streams—Little Conestoga Creek, Mill Creek, Conestoga River, and Pequea Creek—10, 12, 15, and 18 percent, respectively, had atrazine concentrations greater than 3.0 micrograms per liter, the U.S. Environmental Protection Agency maximum contaminant level. Loads of atrazine, metolochlor, and simazine were greater than loads of any other herbicides. The largest loads were transported during 1994. Loads of atrazine transported by the four streams during periods of storm- flow from May to September 1994 totaled 3.46, 28.3, 263, and 46.8 pounds, respectively. The total loads of atrazine transported by the four streams?Little Conestoga Creek, Mill Creek, Conestoga River, and Pequea Creek—during calendar year 1994 were 6.48, 54.1, 498, and 102 pounds, respectively. A little less than half the atrazine load transported by each stream—45, 39, 42, and 42 percent, respectively—was transported during storms that occurred from May through September.Average annual yields of atrazine for the period 1992-95 were 0.59, 0.64, 0.68, and 0.51 pounds per square mile from the Little Conestoga Creek, Mill Creek, Conestoga River, and Pequea Creek, respectively. Average annual yields of simazine were 0.36, 1.2, 0.54, and 0.48 pounds per square mile, respectively, and average annual yields of metolachlor were 0.46, 0.49, 0.54, and 0.31 pounds per square mile, respectively. Less than 1 percent of both the atrazine and metolachlor that was applied to all basins was transported by streamflow.

Hydrologic and land-use factors associated with herbicides and nitrate in near-surface aquifers

USGS Publications Warehouse

Burkart, Michael R.; Kolpin, Dana W.

1993-01-01

Selected herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) metabolites, and NO−3 were examined in near-surface unconsolidated and bedrock aquifers in the midcontinental USA to study the hydrogeologic, spatial, and seasonal distribution of these contaminants. Groundwater samples were collected from 303 wells during the spring and late summer of 1991. At least one herbicide or atrazine metabolite was detected in 24% of the samples collected for herbicide analysis (reporting limit 0.05 µg/L). No herbicide concentration exceeded the USEPA's maximum contaminant level (MCL) or health advisory level. The most frequently detected compound was the at razine metabolite deethylatrazine [2-amino-4-chloro-6-(isopropylamino)-s-triazine] followed by atrazine, deisopropylatrazine [2-amino-4-chloro-6-(ethylamino)-s-triazine], prometon (2,4-bis(isopropylamino)-6-methyoxy-s-triazine), metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1methylethyl)acetamide], alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], metribuzin [4-amino-6-(tert-butyl)-3-methylthio-as-triazine-5(4H)-one], simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], and cyanazine [2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile]. Nitrite plus nitrate, as nitrogen (N), exceeding 3.0 mg/L (excess NO−3), was found in 29% of the samples, and 6% had −3exceeding the MCL of 10 mg/L. Ammonium as N was detected in excess of 0.01 mg/L in 78% of the samples. A nonlinear increase in the frequency of atrazine detection occurred with decreases in reporting limit. The frequency of atrazine residue detection (atrazine + deethylatrazine + deisopropylatrazine) was 25% greater than for atrazine alone. Herbicide detections and excess NO−3 were notably lacking in the eastern part of the study region where it was estimated that herbicide and fertilizer use were among the largest in the region. Prometon, the second most frequently detected herbicide, was associated with non-agricultural land use. Herbicide and excess NO−3 were more frequent in unconsolidated aquifers than in bedrock aquifers. Aquifer depth, as direct measurement of proximity to recharge sources, was inversely related to frequency of herbicide detection and excess NO−3.

Pesticides in rain in four agricultural watersheds in the United States

USGS Publications Warehouse

Vogel, J.R.; Majewski, M.S.; Capel, P.D.

2008-01-01

Rainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with atrazine (70%) and metolachlor (83%) detected at every site. Dacthal, acetochlor, simazine, alachlor, and pendimethalin were detected in more than 50% of the samples. Chlorpyrifos, carbaryl, and diazinon were the only insecticides among the 10 most frequently detected compounds. Of the remaining pesticide parent compounds, 18 were detected in fewer than 30% of the samples, and 13 were not detected. The most frequently detected degradates were deethylatrazine; the oxygen analogs (OAs) of the organophosphorus insecticides chlorpyrifos, diazinon, and malathion; and 1-napthol (degradate of carbaryl). Deethylatrazine was detected in nearly 70% of the samples collected in Maryland, Indiana, and Nebraska but was detected only once in California. The OAs of chlorpyrifos and diazinon were detected primarily in California. Degradates of the acetanilide herbicides were rarely detected in rain, indicating that they are not formed in the atmosphere or readily volatilized from soils. Herbicides accounted for 91 to 98% of the total pesticide mass deposited by rain except in California, where insecticides accounted for 61% in 2004. The mass of pesticides deposited by rainfall was estimated to be less than 2% of the total applied in these agricultural areas. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Improving alachlor biodegradability by ferrate oxidation.

PubMed

Zhu, Jian-Hang; Yan, Xi-Luan; Liu, Ye; Zhang, Bao

2006-07-31

Alachlor can be recalcitrant when present at high concentrations in wastewater. Ferrate oxidation was used as a pretreatment to improve its biodegradability and was evaluated by monitoring alachlor elimination and removal of COD(Cr) (chemical oxygen demand determined by potassium dichromate) during the oxidation process up to a value compatible with biological treatment. Ferrate oxidation resulted in elimination of alachlor followed by degradation of its intermediates. High pH suppressed alachlor removal and COD(Cr) removal due to the low redox potential of ferrate ions. Although alachlor can be totally eliminated within 10 min under optimized conditions (alachlor, 40 mg l(-1); ferrate:alachlor molar ratio, 2; and pH 7.0), its complete mineralization cannot be achieved by ferrate oxidation alone. Alachlor solution treated by ferrate for 10 min inhibited an up-flow biotreatment with activated sludge. The biodegradability of ferrate-pretreated solution improved when the treatment was increased to 20 min, at the point of which BOD(5)/COD(Cr) ratio of the treated solution was increased to 0.87 from 0.35 after 10 min treatment. Under optimized conditions, ferrate oxidation for 20 min resulted in total elimination of alachlor, partial removal of COD(Cr) and the ferrate-treated solution could be effectively treated by the up-flow activated sludge process.

Ultrasound-assisted extraction and solid-phase extraction for the simultaneous determination of five amide herbicides in fish samples by gas chromatography with electron capture detection.

PubMed

Qu, Zhipeng; Bai, Xiuzhi; Zhang, Ting; Yang, Zhaoguang

2017-03-01

An efficient sample extraction and clean-up method was developed for simultaneous determination of five amide herbicides (alachlor, acetochlor, propisochlor, metazachlor, and butachlor) in fish samples. The protocol consisted of ultrasound-assisted solvent extraction and solid-phase extraction clean-up. In detail, aliquots of homogenized fish flesh were thoroughly mixed with 20 mL of n-hexane and then extracted with ultrasonication for 40 min. Each sample was centrifuged and the supernatant was collected for the subsequent clean-up. For the sample preparation, the above supernatant was processed with a C 18 column with 3 mL of dichloromethane/n-hexane (1:1, v/v) as the eluant. Then the samples were analyzed by gas chromatography with electron capture detection. The correlation coefficients of the five calibration curves were 0.9976-0.9998 (n = 3). The limits of detection (S/N = 3, n = 11) and limits of quantification (S/N = 10, n = 11) were 0.19-0.42 and 0.63-1.39 μg/kg, respectively. The recoveries of this method were 71.2-92.6% with good precision (<4.7% relative standard deviations, n = 6). The developed method was successfully applied to monitor the five amide herbicides in fish samples collected from different cities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation of alachlor in aqueous solution by using hydrodynamic cavitation.

PubMed

Wang, Xikui; Zhang, Yong

2009-01-15

The degradation of alachlor aqueous solution by using hydrodynamic cavitation was systematically investigated. It was found that alachlor in aqueous solution can be deomposed with swirling jet-induced cavitation. The degradation can be described by a pseudo-first-order kinetics and the degradation rate was found to be 4.90x10(-2)min(-1). The effects of operating parameters such as fluid pressure, solution temperature, initial concentration of alachlor and medium pH on the degradation rates of alachlor were also discussed. The results showed that the degradation rates of alachlor increased with increasing pressure and decreased with increasing initial concentration. An optimum temperature of 40 degrees C existed for the degradation rate of alachlor and the degradation rate was also found to be slightly depend on medium pH. Many degradation products formed during the process, and some of them were qualitatively identified by GC-MS.

Determination of herbicides in environmental water samples by simultaneous in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction and silylation followed by GC-MS.

PubMed

Suárez, Ruth; Clavijo, Sabrina; González, Alba; Cerdà, Víctor

2018-03-01

An on-line, fast, simple, selective, and sensitive method has been developed for the determination of three herbicides belonging to the following families: triazines (atrazine), chloroacetamide (alachlor), and phenoxy (2,4-dichlorophenoxyacetic acid) in water samples. The method involves an in-syringe magnetic stirring-assisted dispersive liquid-liquid microextraction along with simultaneous silylation prior to their determination by gas chromatography with mass spectrometry. Extraction, derivatization, and preconcentration have been simultaneously performed using acetone as dispersive solvent, N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide as derivatization agent and trichloroethylene as extraction solvent. After stirring for 180 s, the sedimented phase was transferred to a rotary micro-volume injection valve (3 μL) and introduced by an air stream into gas chromatograph with mass spectrometry detector. Recovery and enrichment factors were 87.2-111.2% and 7.4-10.4, respectively. Relative standard deviations were in the ranges of 6.6-7.4 for intraday and 9.2-9.6 for interday precision. The detection limits were in the range of 0.045-0.03 μg/L, and good linearity was observed up to 200 μg/L, with R 2 ranging between 0.9905 and 0.9964. The developed method was satisfactorily applied to assess the occurrence of the studied herbicides in groundwater samples. The recovery test was also performed with values between 77 and 117%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrologic data for the Big Spring basin, Clayton County, Iowa, water year 1991

USGS Publications Warehouse

Kalkhoff, S.J.; Kuzniar, R.L.

1994-01-01

Stream discharge, specific conductance, pH, and water temperature were monitored continuously, and monthly water-quality samples were collected at a site on Roberts Creek and at Big Spring. Nitrite plus nitrate as nitrogen concentrations in 27 samples from Roberts Creek at the point where it leaves the study area ranged from 1.8 to 22 mg/L. Herbicide concentrations in 26 samples from the Roberts Creek site ranged from less than 0.10 μg/L (micrograms per liter) to 43 μg/L. Alachlor was detected in 42 percent of the samples; atrazine in 92 percent; and cyanazine and metolachlor in 35 percent of the samples. The total suspended-sediment load discharged in Roberts Creek was about 160,000 tons. At Big Spring, the ground-water discharge point, the daily mean specific conductance ranged from 414 to 788 microsiemens per centimeter at 25 degrees Celsius, the daily median pH ranged from 6.7 to 7.1, and the daily mean water temperature ranged from 8.5 to 13.0 degrees Celsius. Concentrations of nitrite plus nitrate as nitrogen in 23 samples ranged from 4.2 to 17 mg/L. The total measured suspended-sediment discharged from Big Spring was about 17,000 tons. Alachlor was detected in 26 percent; atrazine in 100 percent; cyanazine in 26 percent, and metolachlor in 9 percent of the samples. The maximum atrazine concentration was 16 μg/L.

Coupling solid-phase extraction and enzyme-linked immunosorbent assay for ultratrace determination of herbicides in pristine water

USGS Publications Warehouse

Aga, D.S.; Thurman, E.M.

1993-01-01

Solid-phase extraction (SPE) and enzyme-linked immunosorbent assay (ELISA) were coupled for automated trace analysis of pristine water samples containing 2-chloro-4-ethylamino-6-isopropylamine-s-triazine (atrazine) and 2-chloro-2???,6???-diethyl-N-(methoxymethyl)acetanilide (alachlor). The isolation of the two herbicides on a C18-resin involved the selection of an elution solvent that both removes interfering substances and is compatible with ELISA. Ethyl acetate was selected as the elution solvent followed by a solvent exchange with methanol/water (20/80, % v/v). The SPE-ELISA method has a detection limit of 5.0 ng/L (5 ppt), >90% recovery, and a relative standard deviation of ??10%. The performance of a microtiter plate-based ELISA and a magnetic particle-based ELISA coupled to SPE was also evaluated. Although the sensitivity of the two ELISA methods was comparable, the precision using magnetic particles was improved considerably (??10% versus ??20%) because of the faster reaction kinetics provided by the magnetic particles. Finally, SPE-ELISA and isotope dilution gas chromatography/ mass spectrometry correlated well (correlation coefficient of 0.96) for lake-water samples. The SPE-ELISA method is simple and may have broader applications for the inexpensive automated analysis of other contaminants in water at trace levels.

Simultaneous quantification of acetanilide herbicides and their oxanilic and sulfonic acid metabolites in natural waters.

PubMed

Heberle, S A; Aga, D S; Hany, R; Müller, S R

2000-02-15

This paper describes a procedure for simultaneous enrichment, separation, and quantification of acetanilide herbicides and their major ionic oxanilic acid (OXA) and ethanesulfonic acid (ESA) metabolites in groundwater and surface water using Carbopack B as a solid-phase extraction (SPE) material. The analytes adsorbed on Carbopack B were eluted selectively from the solid phase in three fractions containing the parent compounds (PCs), their OXA metabolites, and their ESA metabolites, respectively. The complete separation of the three compound classes allowed the analysis of the neutral PCs (acetochlor, alachlor, and metolachlor) and their methylated OXA metabolites by gas chromatography/mass spectrometry. The ESA compounds were analyzed by high-performance liquid chromatography with UV detection. The use of Carbopack B resulted in good recoveries of the polar metabolites even from large sample volumes (1 L). Absolute recoveries from spiked surface and groundwater samples ranged between 76 and 100% for the PCs, between 41 and 91% for the OXAs, and between 47 and 96% for the ESAs. The maximum standard deviation of the absolute recoveries was 12%. The method detection limits are between 1 and 8 ng/L for the PCs, between 1 and 7 ng/L for the OXAs, and between 10 and 90 ng/L for the ESAs.

Evaluating agricultural management effects on alachlor availability: Tillage, green manure, and biochar

USDA-ARS?s Scientific Manuscript database

Agricultural and soil management practices have been reported to affect alachlor sorption-desorption and degradation rates. The objectives of this study were to: (a) assess differences in alachlor sorption due to tillage treatments (chisel plow and ridge tillage) on soils from three Midwestern U.S. ...

Are streams in agricultural and urban areas contaminated by pesticides?

USGS Publications Warehouse

Kimbrough, R.A.

1995-01-01

To answer this question, a study of pesticides in streams in a small agricultural area and a small urban area in Colorado was conducted in 1993 by the U.S. Geological Survey (USGS) as part of the National Water-Quality Assessment (NAWQA) program. The results indicate that pesticides are present in streams, and both agricultural and urban areas are probable sources of the contamination. In the agricultural area, 30 pesticides were detected and in the urban area, 26 pesticides were detected at least once during the thirteen month study. In the agricultural area, the herbicides alachlor (two samples) and cyanazine (four samples) and the insecticide diazinon (one sample) were the only pesticides that exceeded the U.S. Environmental Protection Agency's maximum contaminant levels (MCLs) or health advisory levels (HALs) for drinking water. No pesticides exceeded MCLs or HALs in the urban area.

Herbicide and nitrate distribution in central Iowa rainfall

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatfield, J.L.; Prueger, J.H.; Pfeiffer, R.L.

Herbicides are detected in rainfall; however, these are a small fraction of the total applied. This study was designed to evaluate monthly and annual variation in atrazine (6-chloro-N-ethyl-N{prime}-(1-methylethyl)-1,3,5-triazine-2,4-diamine), alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide), metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide), and NO{sub 3}-N concentrations in rainfall over Walnut Creek watershed south of Ames, IA. The study began in 1991 and continued through 1994. Within the watershed, two wet/dry precipitation samplers were positioned 4 km apart. Detections varied during the year with >90% of the herbicide detections occurring in April through early July. Concentrations varied among events from nondetectable amounts to concentrations of 154 {mu}g L{sup {minus}1}, which occurredmore » when atrazine was applied during an extremely humid day immediately followed by rainfall of <10 mm that washed spray drift from the atmosphere. This was a local scale phenomenon, because the other collector had a more typical concentration of 1.7 {mu}g L{sup {minus}1} with an 8-mm rainfall. VAriation between the two collectors suggests that local scale meteorological processes affect herbicide movement. Yearly atrazine deposition totals were >100 {mu}g m{sup {minus}2} representing <0.1% of the amount applied. Nitrate-N concentrations in precipitation were uniformly distributed throughout the year and without annual variation in the concentrations. Deposition rates of NO{sub 3}-N were about 1.2 g m{sup {minus}2}. Annual loading onto the watershed was about 25% of the amount applied from all forms of N fertilizers. Movement and rates of deposition provide an understanding of the processes and magnitude of the impact of agriculture on the environment. 7 refs., 5 figs., 3 tabs.« less

Herbicide Transport and Transformations in the Unsaturated Zone of Three Small Agricultural Basins with Corn and Soybean Row Crops

NASA Astrophysics Data System (ADS)

Hancock, T. C.; Vogel, J. R.; Sandstrom, M. W.; Capel, P. D.; Bayless, R. E.; Webb, R. M.

2006-05-01

In the United States, herbicides are among the most significant nonpoint-source pollutants and were applied to 95% of all fields in corn production and 97% of all fields in soybean production in 2003 and 2004. The United States Geological Survey (USGS) has conducted a study on select herbicides in the unsaturated zone under corn and soybean fields in three predominantly agricultural basins: Morgan Creek (Maryland), Leary Weber Ditch within Sugar Creek (Indiana), and Maple Creek (Nebraska). In 2004, the Morgan Creek and Leary Weber Ditch fields were in soybeans and the Maple Creek fields were in corn. The Maple Creek fields were irrigated, whereas those in Morgan Creek and Leary Weber Ditch were not. Similarities and differences in agricultural management practices, climatic conditions, and natural features, such as soil types and geology, were evaluated as part of the study. In general, the amounts of herbicides entering the unsaturated zone from rain in these basins were minor (1%) compared to amounts commonly applied to the land surface during agricultural practices. Few herbicides were detected on solid core samples from the unsaturated zones of these basins. An exception was found at a Morgan Creek site in an upland recharge area with sandier soils. Here, atrazine concentrations were highest in the near surface solids and decreased with depth. In the unsaturated-zone porewater of the Morgan Creek Basin, parent triazine and acetanilide herbicides were detected and only at the site in the upland recharge area at relatively low concentrations at depths greater than 4 meters, probably because these compounds had not been applied for several years. At the Morgan Creek and Leary Weber Ditch sites, acetanilide metabolites were frequently detected in the unsaturated-zone porewater. In general, the fraction of metolachlor ethane sulfonic acid (ESA) relative to the total mass of parent and metabolites increased with depth overall and at several individual sampling locations this fraction increased over time. At the Maple Creek sites, atrazine, metalochlor, acetochlor, and alachlor were detected, typically at concentrations higher than their metabolites. The Maple Creek site is influenced by focused recharge, macropore flow, and variable soil-moisture retention properties in soils that transition from loess to sand.

Primary and complex stressors in polluted mediterranean rivers: Pesticide effects on biological communities

NASA Astrophysics Data System (ADS)

Ricart, Marta; Guasch, Helena; Barceló, Damià; Brix, Rikke; Conceição, Maria H.; Geiszinger, Anita; José López de Alda, Maria; López-Doval, Julio C.; Muñoz, Isabel; Postigo, Cristina; Romaní, Anna M.; Villagrasa, Marta; Sabater, Sergi

2010-03-01

SummaryWe examined the presence of pesticides in the Llobregat river basin (Barcelona, Spain) and their effects on benthic biological communities (invertebrates and diatoms). The Llobregat river is one of Barcelona's major drinking water resources. It has been highly polluted by industrial, agricultural, and urban wastewaters, and—as a typical Mediterranean river—is regularly subjected to periodic floods and droughts. Water scarcity periods result in reduced water flow and dilution capacity, increasing the potential environmental risk of pollutants. Seven sites were selected, where we analysed the occurrence of 22 pesticides (belonging to the classes of triazines, organophosphates, phenylureas, anilides, chloroacetanilides, acidic herbicides and thiocarbamates) in the water and sediment, and the benthic community structure. Biofilm samples were taken to measure several metrics related to both the algal and bacterial components of fluvial biofilms. Multivariate analyses revealed a potential relationship between triazine-type herbicides and the distribution of the diatom community, although no evidence of disruption in the invertebrate community distribution was found. Biofilm metrics were used as response variables rather than abundances of individual species to identify possible cause-effect relationships between pesticide pollution and biotic responses. Certain effects of organophosphates and phenylureas in both structural and functional aspects of the biofilm community were suggested, but the sensitivity of each metric to particular stressors must be assessed before we can confidently assign causality. Complemented with laboratory experiments, which are needed to confirm causality, this approach could be successfully incorporated into environmental risk assessments to better summarise biotic integrity and improve the ecological management.

Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process.

PubMed

Qiang, Zhimin; Liu, Chao; Dong, Bingzhi; Zhang, Yalei

2010-01-01

The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced. 2009 Elsevier Ltd. All rights reserved.

Airborne pesticide residues along the Mississippi River

USGS Publications Warehouse

Majewski, M.S.; Foreman, W.T.; Goolsbys, D.A.; Nakagaki, N.

1998-01-01

The occurrence, concentration, and geographical distribution of agricultural pesticides were determined in air over the Mississippi River from New Orleans, LA, to St. Paul, MN, during the first 10 days of June 1994. Air samples were collected from a research vessel by pulling air through polyurethane foam plugs at about 100 L/min for up to 24 h. Each sample was analyzed for 42 pesticides and 3 pesticide transformation products. Twenty- five compounds-15 herbicides, 7 insecticides, and 3 pesticide transformation products-were detected in one or more samples with concentrations ranging from 0.05 to 80 ng/m3. Alachlor, chlorpyrifos, diazinon, fonofos, malathion, methyl parathion, metolachlor, metribuzin, pendimethalin, and trifluralin were detected in 80% or more of the samples. The highest concentrations for chlorpyrifos (1.6 ng/m3), diazinon (0.36 ng/m3), and malathion (4.6 ng/m3) all occurred near major metropolitan areas. These samples represent a 'snapshot in time', a spatial and temporal integration of which pesticides were present in the air during each sampling period. The occurrence and atmospheric concentrations of the observed pesticides were most closely related to their use on cropland within 40 km of the river.The occurrence, concentration, and geographical distribution of agricultural pesticides were determined in air over the Mississippi River from New Orleans, LA, to St. Paul, MN, during the first 10 days of June 1994. Air samples were collected from a research vessel by pulling air through polyurethane foam plugs at about 100 L/min for up to 24 h. Each sample was analyzed for 42 pesticides and 3 pesticide transformation products. Twenty-five compounds-15 herbicides, 7 insecticides, and 3 pesticide transformation products-were detected in one or more samples with concentrations ranging from 0.05 to 80 ng/m3. Alachlor, chlorpyrifos, diazinon, fonofos, malathion, methyl parathion, metolachlor, metribuzin, pendimethalin, and trifluralin were detected in 80% or more of the samples. The highest concentrations for chlorpyrifos (1.6 ng/m3), diazinon (0.36 ng/m3), and malathion (4.6 ng/m3) all occurred near major metropolitan areas. These samples represent a 'snapshot in time', a spatial and temporal integration of which pesticides were present in the air during each sampling period. The occurrence and atmospheric concentrations of the observed pesticides were most closely related to their use on cropland within 40 km of the river.

Occurrence of pesticides in groundwater and sediments and mineralogy of sediments and grain coatings underlying the Rutgers Agricultural Research and Extension Center, Upper Deerfield, New Jersey, 2007

USGS Publications Warehouse

Reilly, Timothy J.; Smalling, Kelly L.; Meyer, Michael T.; Sandstrom, Mark W.; Hladik, Michelle; Boehlke, Adam R.; Fishman, Neil S.; Battaglin, William A.; Kuivila, Kathryn

2014-01-01

Water and sediment samples were collected from June through October 2007 from seven plots at the Rutgers Agricultural Research and Extension Center in Upper Deerfield, New Jersey, and analyzed for a suite of pesticides (including fungicides) and other physical and chemical parameters (including sediment mineralogy) by the U.S. Geological Survey. Plots were selected for inclusion in this study on the basis of the crops grown and the pesticides used. Forty-one pesticides were detected in 14 water samples; these include 5 fungicides, 13 herbicides, 1 insecticide, and 22 pesticide degradates. The following pesticides and pesticide degradates were detected in 50 percent or more of the groundwater samples: 1-amide-4-hydroxy-chorothalonil, alachlor sulfonic acid, metolachlor oxanilic acid, metolachlor sulfonic acid, metalaxyl, and simazine. Dissolved-pesticide concentrations ranged from below their instrumental limit of detection to 36 micrograms per liter (for metolachlor sulfonic acid, a degradate of the herbicide metolachlor). The total number of pesticides found in groundwater samples ranged from 0 to 29. Fourteen pesticides were detected in sediment samples from continuous cores collected within each of the seven sampled plots; these include 4 fungicides, 2 herbicides, and 7 pesticide degradates. Pesticide concentrations in sediment samples ranged from below their instrumental limit of detection to 34.2 nanograms per gram (for azoxystrobin). The total number of pesticides found in sediment samples ranged from 0 to 8. Quantitative whole-rock and grain-coating mineralogy of sediment samples were determined by x-ray diffraction. Whole-rock analysis indicated that sediments were predominantly composed of quartz. The materials coating the quartz grains were removed to allow quantification of the trace mineral phases present.

Pesticides analysed in rainwater in Alsace region (Eastern France): Comparison between urban and rural sites

NASA Astrophysics Data System (ADS)

Scheyer, Anne; Morville, Stéphane; Mirabel, Philippe; Millet, Maurice

Current-used pesticides commonly applied in Alsace region (Eastern France) on diverse crops (maize, vineyard, vegetables, etc.) were analysed, together with Lindane, in rainwater between January 2002 and June 2003 simultaneously on two sites situated in a typical rural (Erstein, France) and urban area (Strasbourg, France). Rainwater samples were collected on a weekly basis by using two automatic wet only collectors associated with an open collector for the measurement of rainwater height. Pesticides were analysed by GC-MSMS and extracted from rainwater by SPME. Two runs were performed. The first one was performed by using a PDMS (100 μm) fibre for pesticides where direct injection into GC is possible (alachlor, atrazine, azinphos-ethyl, azinphos-methyl, captan, chlorfenvinphos, dichlorvos, diflufenican, α- and β-endosulfan, iprodione, lindane, metolachlor, mevinphos, parathion-methyl, phosalone, phosmet, tebuconazole, triadimefon and trifluralin). The second run was performed by using PDMS/DVB fibre and this run concerns pesticides where a preliminary derivatisation step with pentafluorobenzylbromide (PFBBr) is required for very low volatiles (bromoxynil,2,4-MCPA, MCPP and 2,4-D) or thermo labiles (chlorotoluron, diuron and isoproturon) pesticides. Results showed that the more concentrated pesticides detected were those used as herbicides in large quantities in Alsace region for maize crops (alachlor, metolachlor and atrazine). Maximum concentrations for these herbicides have been measured during intensive applications periods on maize crops following by rapid decrease immediately after use. For Alachlor, most important peaks have been observed between 21 and 28 April 2003 (3327 ng L -1 at Erstein and 5590 ng L -1 at Strasbourg). This is also the case for Metolachlor where most important peak was observed during the same week. Concentrations of pesticides measured out of application periods were very low for many pesticides and some others where never detected during this period. This is the case for diflufenican which was detected only during application. Two important peaks of concentrations were observed; a first one (101 ng L -1) in Erstein in November 2002 (4-11 November) and a second one (762 ng L -1) also in Erstein (28 April-15 May). The same behaviour can be seen for chlorfenvinphos and phosalone which have been detected, respectively, 2 and 4 times in Erstein and Strasbourg at high concentrations (28 April 2003-15 May 2003, 187 ng L -1 of phosalone and 157 ng L -1 of chlorfenvinphos in Erstein). MCPP, 2,4 MCPA and 2,4-D have been detected at high concentrations in rainwater but for the other pesticides very episodically and mainly during their use in agriculture. Maximal concentrations of MCPP and 2,4 MCPA have been measured in Erstein between 28 April and 15 May (904 and 746 ng L -1, respectively). Comparison between rural and urban sites showed that concentrations in rural areas are generally higher except for pesticides commonly applied in urban areas like Diuron. No seasonal phenomenon was observed for Diuron. This herbicide has been detected in practically all of the rainwater samples in Strasbourg (40/41) with a maximum of 1025 ng L -1 (16-23 September 2002) in 38 samples on 41 in Erstein with a maximum of 317 ng L -1 (15-23 October 2002). The total concentration of Diuron measured between 4 March 2002 and 20 July 2003 is of 4721 ng L -1 in Strasbourg and 5025 ng L -1 in Erstein. This result shows that wet deposition of Diuron in urban and rural sites was equivalent and can be explained by the "urban use" of this molecule together with its potential persistence.

Experimental design approach to the optimization of ultrasonic degradation of alachlor and enhancement of treated water biodegradability.

PubMed

Torres, Ricardo A; Mosteo, Rosa; Pétrier, Christian; Pulgarin, Cesar

2009-03-01

This work presents the application of experimental design for the ultrasonic degradation of alachlor which is pesticide classified as priority substance by the European Commission within the scope of the Water Framework Directive. The effect of electrical power (20-80W), pH (3-10) and substrate concentration (10-50mgL(-1)) was evaluated. For a confidential level of 90%, pH showed a low effect on the initial degradation rate of alachlor; whereas electrical power, pollutant concentration and the interaction of these two parameters were significant. A reduced model taking into account the significant variables and interactions between variables has shown a good correlation with the experimental results. Additional experiments conducted in natural and deionised water indicated that the alachlor degradation by ultrasound is practically unaffected by the presence of potential *OH radical scavengers: bicarbonate, sulphate, chloride and oxalic acid. In both cases, alachlor was readily eliminated ( approximately 75min). However, after 4h of treatment only 20% of the initial TOC was removed, showing that alachlor by-products are recalcitrant to the ultrasonic action. Biodegradability test (BOD5/COD) carried out during the course of the treatment indicated that the ultrasonic system noticeably increases the biodegradability of the initial solution.

The status of pesticide pollution in surface waters (rivers and lakes) of Greece. Part I. Review on occurrence and levels.

PubMed

Konstantinou, Ioannis K; Hela, Dimitra G; Albanis, Triantafyllos A

2006-06-01

This review evaluates and summarizes the results of long-term research projects, monitoring programs and published papers concerning the pollution of surface waters (rivers and lakes) of Greece by pesticides. Pesticide classes mostly detected involve herbicides used extensively in corn, cotton and rice production, organophosphorus insecticides as well as the banned organochlorines insecticides due to their persistence in the aquatic environment. The compounds most frequently detected were atrazine, simazine, alachlor, metolachlor and trifluralin of the herbicides, diazinon, parathion methyl of the insecticides and lindane, endosulfan and aldrin of the organochlorine pesticides. Rivers were found to be more polluted than lakes. The detected concentrations of most pesticides follow a seasonal variation, with maximum values occurring during the late spring and summer period followed by a decrease during winter. Nationwide, in many cases the reported concentrations ranged in low ppb levels. However, elevated concentrations were recorded in areas of high pesticide use and intense agricultural practices. Generally, similar trends and levels of pesticides were found in Greek rivers compared to pesticide contamination in other European rivers. Monitoring of the Greek water resources for pesticide residues must continue, especially in agricultural regions, because the nationwide patterns of pesticide use are constantly changing. Moreover, emphasis should be placed on degradation products not sufficiently studied so far.

Heterologous expression of the yeast Tpo1p or Pdr5p membrane transporters in Arabidopsis confers plant xenobiotic tolerance.

PubMed

Remy, Estelle; Niño-González, María; Godinho, Cláudia P; Cabrito, Tânia R; Teixeira, Miguel C; Sá-Correia, Isabel; Duque, Paula

2017-07-03

Soil contamination is a major hindrance for plant growth and development. The lack of effective strategies to remove chemicals released into the environment has raised the need to increase plant resilience to soil pollutants. Here, we investigated the ability of two Saccharomyces cerevisiae plasma-membrane transporters, the Major Facilitator Superfamily (MFS) member Tpo1p and the ATP-Binding Cassette (ABC) protein Pdr5p, to confer Multiple Drug Resistance (MDR) in Arabidopsis thaliana. Transgenic plants expressing either of the yeast transporters were undistinguishable from the wild type under control conditions, but displayed tolerance when challenged with the herbicides 2,4-D and barban. Plants expressing ScTPO1 were also more resistant to the herbicides alachlor and metolachlor as well as to the fungicide mancozeb and the Co 2+ , Cu 2+ , Ni 2+ , Al 3+ and Cd 2+ cations, while ScPDR5-expressing plants exhibited tolerance to cycloheximide. Yeast mutants lacking Tpo1p or Pdr5p showed increased sensitivity to most of the agents tested in plants. Our results demonstrate that the S. cerevisiae Tpo1p and Pdr5p transporters are able to mediate resistance to a broad range of compounds of agricultural interest in yeast as well as in Arabidopsis, underscoring their potential in future biotechnological applications.

Occurrence and transport of acetochlor in streams of the Mississippi River Basin

USGS Publications Warehouse

Clark, G.M.; Goolsby, D.A.

1999-01-01

The herbicide acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6- methylphenyl) acetamide] was first used on corn (Zea mays L.) in the USA during the growing season of 1994. By 1996, it was the third most heavily used corn herbicide in the midwestern USA. During the growing season of 1997, 78% of 375 samples collected at 32 stream sites in the Mississippi River Basin contained detectable concentrations of acetochlor. However, concentrations in only 2% of the samples exceeded 2 ??g/L, the maximum annual average concentration allowable in public water supplies derived primarily from surface water. The largest acetochlor concentrations were detected in streams draining basins in parts of Illinois, Indiana, and Iowa. The median concentration of acetochlor in streams was about 10% that of atrazine (6- chloro-N-ethyl-N-isopropyl-1,3,5-triazine-2,4-diamine), about 25% that of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide], about 50% that of cyanazine [2-[[4-chloro-6-(ethylamino)-1,3,5- triazin-2-yl]amino]-2-methylpropionitrile], and about threefold that of alachlor [2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide]. Load estimates indicate that, during the growing season of 1997, agricultural subbasins draining areas of Illinois, Indiana, and Iowa contributed about 37000 kg, or 74%, of the 50 000 kg of acetochlor measured in streams of the Mississippi River Basin.

Nucleophilic substitution at centers other than carbon: reaction at the chlorine of N-chloroacetanilides with triethylamine as the nucleophile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Underwood, G.R.; Dietze, P.E.

1984-12-28

The reaction between triethylamine (TEA) and a series of para-substituted N-chloroacetanilides has been studied in aqueous solution buffered to pHs between 1 and 5. The exclusive product derived from the aromatic moiety is the corresponding acetanilide. The reaction occurs via two parallel pseudo-second-order paths, one acid catalyzed (the Orton-like mechanism), the other uncatalyzed. The uncatalyzed reaction is accelerated by the presence of electron-withdrawing substituents on the aromatic ring and can best be represented as nucleophilic displacement at chlorine. It therefore appears to be the prototype of a convenient class of reactions for the study of displacement reactions at chlorine. Themore » rho value for this reaction is 3.87, indicating substantial negative charge buildup in the aromatic ring during of the transition state. The acid-catalyzed reaction is more complex, presumable involving a protonation equilibrium for the N-chloroacetanilide prior to the rate-determining step similar to that in the Orton reaction. 15 references, 2 figures, 3 tables.« less

Agricultural chemicals in groundwater of the midwestern United States: Relations to land use

USGS Publications Warehouse

Kolpin, D.W.

1997-01-01

To determine the relations between land use and concentrations of selected agricultural chemicals (nitrate, atrazine residue [atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) + deethylatrazinc (2-amino-4-chloro-6-isopropylamino-s-triazine) + deisopropylatrazine (2-amino-4-chloro-6-ethylamino-s-triazine)], and alachlor residue [alachlor, [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide] + alachlor ethanesulfonic acid (alachlor-ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid)] in groundwater, detailed land use information based on accurate measurements from aerial photographs for the 1991 growing season was obtained within a 2-km radius surrounding 100 wells completed in near-surface unconsolidated aquifers in the midwestern USA. The most significant land use factors to the agricultural chemicals examined were: nitrate (amount of irrigated crop production, positive relation), atrazine residue (amount of irrigated crop production, positive relation), and alachlor residue (amount of highly erodible land, inverse relation). The investigation of smaller buffer sizes (size of circular area around sampled wells) proved insightful for this study. Additional land use factors having significant relations to all three agricultural chemicals were identified using these smaller buffer radii. The most significant correlations (correlation maxima) generally occurred at ≤500-m for nitrate and ≥1000-m for atrazine residue and alachlor residue. An attempt to improve the statistical relations to land use by taking hydrologic considerations into account (removing land outside the estimated most probable recharge area from the statistical analysis) was not as successful as anticipated. Only 45% of the nitrate, 32% of the atrazine residue, and 20% of the alachlor residue correlations were improved by a consideration of the estimated most probable recharge area.

Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high-performance liquid chromatography and time-of-flight mass spectrometry

USGS Publications Warehouse

Thurman, E.M.; Ferrer, I.; Parry, R.

2002-01-01

Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750??0.0049 amu and 270.0786??0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098??0.0061 amu and 314.1153??0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation spectra, which did not occur using negative-ion electrospray.

Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high-performance liquid chromatography and time-of-flight mass spectrometry

USGS Publications Warehouse

Thurman, E.M.; Ferrer, Imma; Parry, R.

2002-01-01

Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750+/-0.0049 amu and 270.0786+/-0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098+/-0.0061 amu and 314.1153+/-0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation spectra, which did not occur using negative-ion electrospray.

Methods of Analysis by the U.S. Geological Survey Organic Geochemistry Research Group?Determination of acetamide herbicides and their degradation products in water using online solid-phase extraction and liquid chromatography/mass spectrometry

USGS Publications Warehouse

Lee, E.A.; Strahan, A.P.

2003-01-01

An analytical method for the determination of 6 acetamide herbicides (acetochlor, alachlor, dimethenamid, flufenacet, metolachlor, and propachlor) and 16 of their degradation products in natural water samples using solid-phase extraction and liquid chromatography/mass spectrometry is described in this report. Special consideration was given during the development of the method to prevent the formation of degradation products during the analysis. Filtered water samples were analyzed using octadecylsilane as the solid-phase extraction media on online automated equipment followed by liquid chromatography/mass spectrometry. The method uses only 10 milliliters of sample per injection. Three different water-sample matrices, a reagent-water, a ground-water, and a surface-water sample spiked at 0.10 and 1.0 microgram per liter, were analyzed to determine method performance. Method detection limits ranged from 0.004 to 0.051 microgram per liter for the parent acetamide herbicides and their degradation products. Mean recoveries for the acetamide compounds in the ground- and surface-water samples ranged from 62.3 to 117.4 percent. The secondary amide of acetochlor/metolachlor ethanesulfonic acid (ESA) was recovered at an average rate of 43.5 percent. The mean recoveries for propachlor and propachlor oxanilic acid (OXA) were next lowest, ranging from 62.3 to 95.5 percent. Mean recoveries from reagent-water samples ranged from 90.3 to 118.3 percent for all compounds. Overall the mean of the mean recoveries of all compounds in the three matrices spiked at 0.10 and 1.0 microgram per liter ranged from 89.9 to 100.7 percent, including the secondary amide of acetochlor/metolachlor ESA and the propachlor compounds. The acetamide herbicides and their degradation products are reported in concentrations ranging from 0.05 to 2.0 micrograms per liter. The upper concentration limit is 2.0 micrograms per liter for all compounds without dilution. With the exception of the secondary amide of acetochlor/metolachlor ESA, good precision and accuracy for the chloroacetanalide herbicides and their degradation compounds were demonstrated for the method in buffered reagent water, ground water, and surface water. The extraction method as used did not optimize the recovery of the secondary amide of acetochlor/metolachlor ESA.

Effects of long-term alachlor exposure on hepatic antioxidant defense and detoxifying enzyme activities in crucian carp (Carassius auratus).

PubMed

Yi, Xionghai; Ding, Hui; Lu, Yitong; Liu, Haohua; Zhang, Min; Jiang, Wei

2007-07-01

Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and also an environmental estrogen. In this paper, the physiological and biochemical perturbations of crucian carp (Carassius auratus) exposed to alachlor at different concentrations over 60 days were investigated. The gonadosomatic index (GSI) and hepatosomatic index (HSI) were measured. The activity of hepatic antioxidant defense and detoxifying enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the content of glutathione (GSH) were determined and compared with the control group. The result showed that GSI and HSI decreased significantly (P<0.05) in almost all treatments. The activities of SOD, CAT and GST were induced continuously (P<0.05), while the content of reduced glutathione (GSH) was inhibited on the whole. These changes reflect that the antioxidant systems of the tested fishes were affected. The possible defense mechanistic implications about the changes were thus discussed. Furthermore, hepatic SOD and GST were sensitive to alachlor at low concentration, indicating that they might be potential biomarkers in early detection of alachlor contamination in aquatic ecosystems.

Alachlor

Integrated Risk Information System (IRIS)

Alachlor ; CASRN 15972 - 60 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

40 CFR 180.249 - Alachlor; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., calculated as alachlor in or on the following raw agricultural commodities. Commodity Parts per million Beans, dry 0.1 Beans, succulent lima 0.1 Cattle, fat 0.02 Cattle, meat byproducts 0.02 Cattle, meat 0.02 Corn...

40 CFR 180.249 - Alachlor; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., calculated as alachlor in or on the following raw agricultural commodities. Commodity Parts per million Beans, dry 0.1 Beans, succulent lima 0.1 Cattle, fat 0.02 Cattle, meat byproducts 0.02 Cattle, meat 0.02 Corn...

40 CFR 180.249 - Alachlor; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., calculated as alachlor in or on the following raw agricultural commodities. Commodity Parts per million Beans, dry 0.1 Beans, succulent lima 0.1 Cattle, fat 0.02 Cattle, meat byproducts 0.02 Cattle, meat 0.02 Corn...

40 CFR 180.249 - Alachlor; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., calculated as alachlor in or on the following raw agricultural commodities. Commodity Parts per million Beans, dry 0.1 Beans, succulent lima 0.1 Cattle, fat 0.02 Cattle, meat byproducts 0.02 Cattle, meat 0.02 Corn...

Ground-water quality in northeastern St. Joseph County, Indiana

USGS Publications Warehouse

Fenelon, J.M.; Bayless, E. Randall; Watson, Lee R.

1995-01-01

No industrial organic compounds were detected in the water samples. Four pesticides - alachlor, carbofuran, metolachlor, and triazines - were detected in water samples; the highest pesticide concentration in a water sample was 1.0 microgram per liter of alachlor.

40 CFR 180.249 - Alachlor; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., calculated as alachlor in or on the following raw agricultural commodities. Commodity Parts per million Beans, dry 0.1 Beans, succulent lima 0.1 Cattle, fat 0.02 Cattle, meat byproducts 0.02 Cattle, meat 0.02 Corn...

Pesticide fate and transport throughout unsaturated zones in five agricultural settings, USA

USGS Publications Warehouse

Hancock, T.C.; Sandstrom, M.W.; Vogel, J.R.; Webb, R.M.T.; Bayless, E.R.; Barbash, J.E.

2008-01-01

Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and atrazine were applied at a Nebraska site the same year as sampling, and focused recharge coupled with the short time since application resulted in their movement in the unsaturated zone 9 m below the surface. At other sites where the herbicides were applied 1 to 2 yr before sampling, only degradates were found in soil water. Transformations of herbicides were evident with depth and during the 4-mo sampling time and reflected the faster degradation of metolachlor oxanilic acid and persistence of metolachor ethanesulfonic acid. The fraction of metolachlor ethanesulfonic acid relative to metolachlor and metolachlor oxanilic acid increased from 0.3 to > 0.9 at a site in Maryland where the unsaturated zone was 5 m deep and from 0.3 to 0.5 at the shallowest depth. The flux of pesticide degradates from the deepest sites to the shallow ground water was greatest (3.0–4.9 μmol m−2 yr−1) where upland recharge or focused flow moved the most water through the unsaturated zone. Flux estimates based on estimated recharge rates and measured concentrations were in agreement with fluxes estimated using an unsaturated-zone computer model (LEACHM).

Pesticides in groundwater in the Anacostia River and Rock Creek watersheds in Washington, D.C., 2005 and 2008

USGS Publications Warehouse

Koterba, Michael T.; Dieter, Cheryl A.; Miller, Cherie V.

2010-01-01

The U.S. Geological Survey (USGS), in cooperation with the District Department of the Environment, conducted a groundwater-quality investigation to (a) determine the presence, concentrations, and distribution of selected pesticides in groundwater, and (b) assess the presence of pesticides in groundwater in relation to selected landscape, hydrogeologic, and groundwater-quality characteristics in the shallow groundwater underlying the Anacostia River and Rock Creek watersheds in Washington, D.C. With one exception, well depths were 100 feet or less below land surface. The USGS obtained or compiled ancillary data and information on land use (2001), subsurface sediments, and groundwater samples from 17 wells in the lower Anacostia River watershed from September through December 2005, and from 14 wells in the lower Anacostia River and lower Rock Creek watersheds from August through September 2008. Twenty-seven pesticide compounds, reflecting at least 19 different types of pesticides, were detected in the groundwater samples obtained in 2005 and 2008. No fungicides were detected. In relation to the pesticides detected, degradate compounds were as or more likely to be detected than applied (parent) compounds. The detected pesticides chiefly reflected herbicides commonly used in urban settings for non-specific weed control or insecticides used for nonspecific haustellate insects (insects with specialized mouthparts for sucking liquid) or termite-specific control. Detected pesticides included a combination of pesticides currently (2008) in use, banned or under highly restricted use, and some that had replaced the banned or restricted-use pesticides. The presence of banned and restricted-use pesticides illustrates their continued persistence and resistance to complete degradation in the environment. The presence of the replacement pesticides indicates the susceptibility of the surficial aquifer to contamination irrespective of the changes in the pesticides used. A preliminary review of the data collected in 2005 and 2008 indicated that differences in the surficial geology, land use (as a surrogate for pesticide use), and above-average precipitation for most of 2004 through 2008, as well as differences in the number and performance of USGS laboratory methods used, could have led to more pesticides detected in groundwater samples collected in 2008 than in groundwater samples collected in 2005. Thus, although data from both years of collection were used for interpretive analysis, emphasis was placed on the analysis of the data obtained in 2008. The presence of pesticides in shallow groundwater (less than approximately 100 ft (feet), or 30 m (meters), below land surface) indicated at least the upper surficial aquifer in Washington, D.C. was susceptible to contamination. One or more herbicides or insecticides were detected in groundwater samples collected from 50 percent of the shallow wells sampled in 2005, and from 62 percent of the shallow wells sampled in 2008. Differences among types of pesticides in shallow groundwater were apparent. The most frequently detected class of herbicides was the s-triazine compounds-atrazine, simazine, or prometon, or the atrazine-degradate compounds-2-chloro-4-ethylamino-6-amino-s-triazine (desethylatrazine or CIAT) and 2-chloro-4-isopropylamino-6-amino-s-triazine (hydroxyatrazine or OIET). The next most frequently detected classes of herbicides were the chloroacetanilides, including metolachlor and acetochlor, and the ureic herbicides, including diuron (and degradate, 3,4-dichloroaniline), fluometuron, metsulfuron methyl, sulfameturon, bromacil, and tebuthiuron. Insecticides also were detected, but less frequently than herbicides, with one or more insecticides present in groundwater samples from 38 percent of shallow wells sampled in 2008. Detected insecticides included parent or degradate compounds commonly used for either nonspecific or haustellate (sucking) insects, including chlorpyri

Methods of analysis-Determination of pesticides in sediment using gas chromatography/mass spectrometry

USGS Publications Warehouse

Hladik, Michelle; McWayne, Megan M.

2012-01-01

A method for the determination of 119 pesticides in environmental sediment samples is described. The method was developed by the U.S. Geological Survey (USGS) in support of the National Water Quality Assessment (NAWQA) Program. The pesticides included in this method were chosen through prior prioritization. Herbicides, insecticides, and fungicides along with degradates are included in this method and span a variety of chemical classes including, but not limited to, chloroacetanilides, organochlorines, organophosphates, pyrethroids, triazines, and triazoles. Sediment samples are extracted by using an accelerated solvent extraction system (ASE®, and the compounds of interest are separated from co-extracted matrix interferences (including sulfur) by passing the extracts through high performance liquid chromatography (HPLC) with gel-permeation chromatography (GPC) along with the use of either stacked graphitized carbon and alumina solid-phase extraction (SPE) cartridges or packed Florisil®. Chromatographic separation, detection, and quantification of the pesticides from the sediment-sample extracts are done by using gas chromatography with mass spectrometry (GC/MS). Recoveries in test sediment samples fortified at 10 micrograms per kilogram (μg/kg) dry weight ranged from 75 to 102 percent; relative standard deviations ranged from 3 to 13 percent. Method detection limits (MDLs), calculated by using U.S. Environmental Protection Agency procedures (40 CFR 136, Appendix B), ranged from 0.6 to 3.4 μg/kg dry weight.

Single-step uncalcined N-TiO2 synthesis, characterizations and its applications on alachlor photocatalytic degradations

NASA Astrophysics Data System (ADS)

Suwannaruang, Totsaporn; Wantala, Kitirote

2016-09-01

The aims of this research were to synthesize nitrogen doped TiO2 (N-TiO2) photocatalysts produced by hydrothermal technique and to test the degradation performance of alachlor by photocatalytic process under UV irradiations in the effect of aging temperature and time in the preparation process. The characterizations of synthesized TiO2 such as specific surface area, particle size, phase structure and elements were analyzed by using the Brunauer-Emmett-Teller (BET) technique, Transmission Electron Microscopy (TEM), X-ray Diffractometer (XRD) and Energy Dispersive X-ray spectrometer (EDX), respectively. The Central Composite Design (CCD) was used to design the experiment to determine the optimal condition, main effects and their interactions by using specific surface area, percent alachlor removal and observed first-order rate constant as responses. The kinetic reactions of alachlor degradation were explained by using Langmuir-Hinshelwood expression to confirm the reaction took place on the surface of photocatalyst. The results showed that the effect of aging temperatures was significant on surface area, whereas aging time was insignificant. Additionally, the square term of aging temperature and interaction term were shown significant on the specific surface area as well. The highest specific surface area from response surface at aging temperature between 150-175 °C and aging time between 6-13 h was found in a range of 100-106 m2/g. The average particle size of TiO2 was similar to crystallite size. Therefore, it can be concluded that one particle has only one crystal. The element analysis has shown 10% of nitrogen in TiO2 structure that the energy band-gap about 2.95 eV was found. Although, the effects of aging temperature and time on percent alachlor removal and observed first-order rate constants were insignificant, both terms were significant in term of the square for alachlor photocatalytic degradation. The optimal condition of both responses was achieved at an aging temperature of 145 °C and aging time of 12 h.

Trends in pesticide concentrations in corn-belt streams, 1996-2006

USGS Publications Warehouse

Sullivan, Daniel J.; Vecchia, Aldo V.; Lorenz, David L.; Gilliom, Robert J.; Martin, Jeffrey D.

2009-01-01

Trends in the concentrations of commonly occurring pesticides in the Corn Belt of the United States were assessed, and the performance and application of several statistical methods for trend analysis were evaluated. Trends in the concentrations of 11 pesticides with sufficient data for trend assessment were assessed at up to 31 stream sites for two time periods: 1996–2002 and 2000–2006. Pesticides included in the trend analyses were atrazine, acetochlor, metolachlor, alachlor, cyanazine, EPTC, simazine, metribuzin, prometon, chlorpyrifos, and diazinon.The statistical methods applied and compared were (1) a modified version of the nonparametric seasonal Kendall test (SEAKEN), (2) a modified version of the Regional Kendall test, (3) a parametric regression model with seasonal wave (SEAWAVE), and (4) a version of SEAWAVE with adjustment for streamflow (SEAWAVE-Q). The SEAKEN test is a statistical hypothesis test for detecting monotonic trends in seasonal time-series data such as pesticide concentrations at a particular site. Trends across a region, represented by multiple sites, were evaluated using the regional seasonal Kendall test, which computes a test for an overall trend within a region by computing a score for each season at each site and adding the scores to compute the total for the region. The SEAWAVE model is a parametric regression model specifically designed for analyzing seasonal variability and trends in pesticide concentrations. The SEAWAVE-Q model accounts for the effect of changing flow conditions in order to separate changes caused by hydrologic trends from changes caused by other factors, such as pesticide use.There was broad, general agreement between unadjusted trends (no adjustment for streamflow effects) identified by the SEAKEN and SEAWAVE methods, including the regional seasonal Kendall test. Only about 10 percent of the paired comparisons between SEAKEN and SEAWAVE indicated a difference in the direction of trend, and none of these had differences significant at the 10-percent significance level. This consistency of results supports the validity and robustness of all three approaches as trend analysis tools. The SEAWAVE method is favored, however, because it has less restrictive data requirements, enabling analysis for more site/pesticide combinations, and can incorporate adjustment for streamflow (SEAWAVE-Q) with substantially fewer measurements than the flow-adjustment procedure used with SEAKEN.Analysis of flow-adjusted trends is preferable to analysis of non-adjusted trends for evaluating potential effects of changes in pesticide use or management practices because flow-adjusted trends account for the influence of flow-related variability.Analysis of flow-adjusted trends by SEAWAVE-Q showed that all of the pesticides assessed, except simazine and acetochlor, were dominated by varying degrees of concentration downtrends in one or both analysis periods. Atrazine, metolachlor, alachlor, cyanazine, EPTC, and metribuzin—all major corn herbicides, as well as prometon and chlorpyrifos, showed more prevalent concentration downtrends during 1996–2002 compared to 2000–2006. Diazinon had no clear trends during 1996–2002, but had predominantly downward trends during 2000–2006. Acetochlor trends were mixed during 1996–2002 and slightly upward during 2000–2006, but most of the trends were not statistically significant. Simazine concentrations trended upward at most sites during both 1996–2002 and 2000–2006.Comparison of concentration trends to agricultural-use trends indicated similarity in direction and magnitude for acetochlor, metolachlor, alachlor, cyanazine, EPTC, and metribuzin. Concentration downtrends for atrazine, chlorpyrifos, and diazinon were steeper than agricultural-use downtrends at some sites, indicating the possibility that agricultural management practices may have increasingly reduced transport to streams (particularly atrazine) or, for chlorpyrifos and diazinon, that nonagricultural uses declined substantially. Concentration uptrends for simazine generally were steeper than agricultural-use uptrends, indicating the possibility that nonagricultural uses of this herbicide increased during the study period.

Occurrence, distribution, and transport of pesticides in agricultural irrigation-return flow from four drainage basins in the Columbia Basin Project, Washington, 2002-04, and comparison with historical data

USGS Publications Warehouse

Wagner, Richard J.; Frans, Lonna M.; Huffman, Raegan L.

2006-01-01

Water-quality samples were collected from sites in four irrigation return-flow drainage basins in the Columbia Basin Project from July 2002 through October 2004. Ten samples were collected throughout the irrigation season (generally April through October) and two samples were collected during the non-irrigation season. Samples were analyzed for temperature, pH, specific conductance, dissolved oxygen, major ions, trace elements, nutrients, and a suite of 107 pesticides and pesticide metabolites (pesticide transformation products) and to document the occurrence, distribution, and pesticides transport and pesticide metabolites. The four drainage basins vary in size from 19 to 710 square miles. Percentage of agricultural cropland ranges from about 35 percent in Crab Creek drainage basin to a maximum of 75 percent in Lind Coulee drainage basin. More than 95 percent of cropland in Red Rock Coulee, Crab Creek, and Sand Hollow drainage basins is irrigated, whereas only 30 percent of cropland in Lind Coulee is irrigated. Forty-two pesticides and five metabolites were detected in samples from the four irrigation return-flow drainage basins. The most compounds detected were in samples from Sand Hollow with 37, followed by Lind Coulee with 33, Red Rock Coulee with 30, and Crab Creek with 28. Herbicides were the most frequently detected pesticides, followed by insecticides, metabolites, and fungicides. Atrazine, bentazon, diuron, and 2,4-D were the most frequently detected herbicides and chlorpyrifos and azinphos-methyl were the most frequently detected insecticides. A statistical comparison of pesticide concentrations in surface-water samples collected in the mid-1990s at Crab Creek and Sand Hollow with those collected in this study showed a statistically significant increase in concentrations for diuron and a statistically significant decrease for ethoprophos and atrazine in Crab Creek. Statistically significant increases were in concentrations of bromacil, diuron, and pendimethalin at Sand Hollow and statistically significant decreases were in concentrations of 2,6-diethylanaline, alachlor, atrazine, DCPA, and EPTC. A seasonal Kendall trend test on data from Lind Coulee indicated no statistically significant trends for any pesticide for 1994 through 2004. A comparison of pesticide concentrations detected in this study with those detected in previous U.S. Geological Survey National Water-Quality Assessment studies of the Central Columbia Plateau, Yakima River basin, and national agricultural studies indicated that concentrations in this study generally were in the middle to lower end of the concentration spectrum for the most frequently detected herbicides and insecticides, but that the overall rate of detection was near the high end. Thirty-one of the 42 herbicides, insecticides, and fungicides detected in surface-water samples were applied to the major agricultural crops in the drainage basins, and 11 of the detected pesticides are sold for residential application. Eight of the pesticides detected in surface-water samples were not reported as having any agricultural or residential use. The overall pattern of pesticide use depends on which crops are grown in each drainage basin. Drainage basins with predominantly more orchards have higher amounts of insecticides applied, whereas basins with larger percentages of field crops tend to have more herbicides applied. Pesticide usage was most similar in Crab Creek and Sand Hollow, where the largest total amounts applied were the insecticides azinphos-methyl, carbaryl, and chlorpyrifos and the herbicide EPTC. In Red Rock Coulee basin, DCPA was the most heavily applied herbicide, followed by the fungicide chlorothalonil, the herbicide EPTC, and the insecticides chlorpyrifos and azinphos-methyl. In Lind Coulee, which has a large percentage of dryland agricultural area, the herbicides 2,4-D and EPTC were applied in the largest amount, followed by the fungicide chlorothalonil. The

Reconnaissance of ground-water quality in the Papio-Missouri River Natural Resources District, eastern Nebraska, July through September 1992

USGS Publications Warehouse

Verstraeten, Ingrid M.; Ellis, M.J.

1995-01-01

A reconnaissance of ground-water quality was conducted in the Papio-Missouri River Natural Resources District of eastern Nebraska. Sixty-one irrigation, municipal, domestic, and industrial wells completed in the principal aquifers--the unconfined Elkhorn, Missouri, and Platte River Valley alluvial aquifers, the upland area alluvial aquifers, and the Dakota aquifer--were selected for water-quality sampling during July, August, and September 1992. Analyses of water samples from the wells included determination of dissolved nitrate as nitrogen and triazine and acetanilide herbicides. Waterquality analyses of a subset of 42 water samples included dissolved solids, major ions, metals, trace elements, and radionuclides. Concentrations of dissolved nitrate as nitrogen in water samples from 2 of 13 wells completed in the upland area alluvial aquifers exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level for drinking water of 10 milligrams per liter. Thirty-nine percent of the dissolved nitrate-as-nitrogen concentrations were less than the detection level of 0.05 milligram per liter. The largest median dissolved nitrate-as-nitrogen concentrations were in water from the upland area alluvial aquifers and the Dakota aquifer. Water from all principal aquifers, except the Dakota aquifer, had detectable concentrations of herbicides. Herbicides detected included alachlor (1 detection), atrazine (13 detections), cyanazine (5 detections), deisopropylatrazine (6 detections), deethylatrazine (9 detections), metolachlor (6 detections), metribuzin (1 detection), prometon (6 detections), and simazine (2 detections). Herbicide concentrations did not exceed U.S. Environmental Protection Agency Maximum Contaminant Levels for drinking water. In areas where the hydraulic gradient favors loss of surface water to ground water, the detection of herbicides in water from wells along the banks of the Platte River indicates that the river could act as a line source of herbicides. Water from the alluvial and bedrock aquifers generally was a calcium bicarbonate type and was hard. Two of nine water samples collected from the Dakota aquifer contained calcium sulfate type water. Results of analyses of 42 groundwater samples for major ions, metals, trace elements, and radionuclide constituents indicated that statistically at least one principal aquifer had significant differences in its water chemistry. In general, the water chemistry of the Dakota aquifer was similar to the water chemistry of the upland area alluvial aquifers in areas where there was a hydraulic connection. The water from the Dakota aquifer had large dissolved-solids, calcium, sulfate, chloride, iron, lithium, manganese, and strontium concentrations in areas where the aquifer is thought not to be in hydraulic connection with the Missouri River Valley and upland area alluvial aquifers. Ground-water quality in the Papio-MissouriRiver Natural Resources District is generally suitable for most uses. However, the numerous occurrences of herbicides in water of the Elkhorn and Platte River Valley alluvial aquifers, especially near the Platte River, are of concern because U.S. Environmental Protection Agency Maximum Contaminant Levels could be exceeded. Concentrations in three of nine water samples collected from wells completed in the Dakota aquifer exceeded the U.S. Environmental Protection Agency Maximum Contaminant Levels or Secondary Maximum Contaminant Levels for gross alpha activity, radon-222 activity, dissolved solids, sulfate, or iron. Also of concern are the exceedances of the U.S Environmental Protection Agency proposed Maximum Contaminant Level for radon-222 activity.

Study of processes influencing bioavailability of pesticides in wood-soil systems: Effect of different factors.

PubMed

Marín-Benito, J M; Herrero-Hernández, E; Rodríguez-Cruz, M S; Arienzo, M; Sánchez-Martín, M J

2017-05-01

Lignocellulosic wastes and by-products containing lignin are now available in large amounts from forestry and industrial activities, and could be promising organic materials for the biosorption of pesticides by soils in order to reduce point-source pollution. Adding these materials to soil requires understanding the process of pesticide sorption-desorption by wood-soils, as sorption capacity could increase, with changes in pesticide bioavailability and final fate. The objective of this work was to study the effect that pine and oak wood added to soils had on the sorption/desorption of the pesticides linuron, alachlor, and metalaxyl. Experiments were conducted with two sandy loam and sandy clay soils each amended with two wood doses (5% and 50%) after different incubation times (0, 5 and 12 months). A low wood dose (5%) had no significant impact on the sorption (K f ) of alachlor, but K f increased for linuron (up to 5.4-1.7 times) and metalaxyl (up to 4.4 and 8.6 times) in all wood-soil systems. The results were not significantly different after different incubation times. The desorption results indicated that wood decreases the sorption irreversibility of alachlor, and increases that of linuron and metalaxyl, with a varying effect of the wood-soil incubation time. The addition of a high wood dose to soil (50%) was more significant for increasing the sorption of all the pesticides, and the sorbed amounts remaining after desorption (>49% for linuron, >33% for alachlor and >6% for metalaxyl), although there was no apparent discrimination between the two types of woods. The role of the nature of the organic carbón (K oc values) for sorption was evidenced for alachlor and metalaxyl, but not for linuron. These outcomes are of interest for extending wood application to soil as a barrier for avoiding environmental risk by point-source pollution due to the use and management of pesticides in farming systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Bioadsorber efficiency, design, and performance forecasting for alachlor removal.

PubMed

Badriyha, Badri N; Ravindran, Varadarajan; Den, Walter; Pirbazari, Massoud

2003-10-01

This study discusses a mathematical modeling and design protocol for bioactive granular activated carbon (GAC) adsorbers employed for purification of drinking water contaminated by chlorinated pesticides, exemplified by alachlor. A thin biofilm model is discussed that incorporates the following phenomenological aspects: film transfer from the bulk fluid to the adsorbent particles, diffusion through the biofilm immobilized on adsorbent surface, adsorption of the contaminant into the adsorbent particle. The modeling approach involved independent laboratory-scale experiments to determine the model input parameters. These experiments included adsorption isotherm studies, adsorption rate studies, and biokinetic studies. Bioactive expanded-bed adsorber experiments were conducted to obtain realistic experimental data for determining the ability of the model for predicting adsorber dynamics under different operating conditions. The model equations were solved using a computationally efficient hybrid numerical technique combining orthogonal collocation and finite difference methods. The model provided accurate predictions of adsorber dynamics for bioactive and non-bioactive scenarios. Sensitivity analyses demonstrated the significance of various model parameters, and focussed on enhancement in certain key parameters to improve the overall process efficiency. Scale-up simulation studies for bioactive and non-bioactive adsorbers provided comparisons between their performances, and illustrated the advantages of bioregeneration for enhancing their effective service life spans. Isolation of microbial species revealed that fungal strains were more efficient than bacterial strains in metabolizing alachlor. Microbial degradation pathways for alachlor were proposed and confirmed by the detection of biotransformation metabolites and byproducts using gas chromatography/mass spectrometry.

TRANSFORMATIONS OF CHLORO-S-TRIAZINE AND CHLOROACETANILIDE AGROCHEMICALS IN NATURAL AND POLYSULFIDE-FORTIFIED SULFIDIC WATERS. (R826269)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Water-quality assessment of the Albemarle-Pamlico drainage basin, North Carolina and Virginia; characterization of suspended sediment, nutrients, and pesticides

USGS Publications Warehouse

Harned, Douglas; McMahon, Gerard; Spruill, T.B.; Woodside, M.D.

1995-01-01

The 28,000-square-mile Albemarle-Pamlico drainage basin includes the Roanoke, Dan, Chowan Tar, and Neuse Rivers. The basin extends through four physiographic provinces in North Carolina and Virginia-Valley and Ridge, Blue Ridge, Piedmont and Coastal Plain. The spatial and temporal trends in ground-water and riverine water quality in the study area were characterized by using readily available data sources The primary data sources that were used included the U.S. Geological Survey's National Water Data Storage and Retrieval System (WATSTORE) database, the U.S. Environmental Protection Agency's Storage and Retrieval System (STORET) database, and results of a few investigations of pesticide occurrence. The principal water-quality constituents examined were suspended sediment, nutrients, and pesticides. The data examined generally spanned the period from 1950 to 1993. The only significant trends in suspended sediment were detected at three Chowan River tributary sites which showed long-term decreases. Suspended- and total-solids concentrations have decreased throughout the Albemarle-Pamlico drainage basin. The decreases are probably a result of (1) construction of new lakes and ponds in the basin, which trap solids, (2) improved agricultural soil management, and (3) improved wastewater treatment. Nutrient point sources are much less than nonpoint nutrient sources at the eight NASQAN basins examined for nutrient loads. The greatest nitrogen inputs are associated with crop fertilizer and biological nitrogen fixation by soybeans and peanuts, whereas atmospheric and animal-related nitrogen inputs are comparable in magnitude. The largest phosphorus inputs are associated with animal wastes. The most commonly detected pesticides in surface water in the STORET database were atrazine and aldrin.Intensive organonitrogen herbicide sampling of Chicod Creek in 1992 showed seasonal variations in pesticide concentration. The most commonly detected herbicides were atrazine, alachlor, metolachlor, prometon, and metribuzin. No relation between streamflow and pesticide concentration was evident.

Enhanced retention of linuron, alachlor and metalaxyl in sandy soil columns intercalated with wood barriers.

PubMed

Rodríguez-Cruz, M S; Ordax, J M; Arienzo, M; Sánchez-Martín, M J

2011-03-01

A study has been made of the effect a reactive barrier made of pine (softwood) or oak (hardwood) wood intercalated in a sandy soil column has on the retention of linuron, alachlor and metalaxyl (pesticides with contrasting physicochemical characteristics). The leaching of pesticides has been carried out under a saturated flow regime and breakthrough curves (BTCs) have been obtained at flow rates of 1 m Lmin(-1) (all pesticides) and 3 m Lmin(-1) (linuron). The cumulative curves in the unmodified soil indicate a leaching of pesticides >80% of the total amount of compound added. After barrier intercalation, linuron leaching decreases significantly and a modification of the leaching kinetics of alachlor and metalaxyl has been observed. The theoretical R factors increased ∼2.6-3.3, 1.2-1.6-fold, and 1.4-1.7-fold and the concentration of the maximum peak decreased ∼6-12-fold, 2-4-fold and 1.2-2-fold for linuron, alachlor and metalaxyl, respectively. When considering the three pesticides, significant correlations have been found between the theoretical retardation factor (R) and the pore volume corresponding to the maximum peaks of the BTCs (r=0.77; p<0.05) or the total volume leached (r=-0.78; p<0.05). The results reveal the efficacy of reactive wood barriers to decrease the leaching of pesticides from point sources of pollution depends on the type of wood, the hydrophobicity of the pesticide and the adopted water flow rate. Pine was more effective than oak in decreasing the leaching of hydrophobic pesticide linuron or in decreasing the maximum peak concentration of the less hydrophobic pesticides in soils. Efficacy of these wood barriers was limited for the least hydrophobic pesticide metalaxyl. Copyright © 2010 Elsevier Ltd. All rights reserved.

Characterization of sorption processes for the development of low-cost pesticide decontamination techniques.

PubMed

Rojas, Raquel; Vanderlinden, Eva; Morillo, José; Usero, José; El Bakouri, Hicham

2014-08-01

The adsorption/desorption behavior of four pesticides (atrazine, alachlor, endosulfan sulfate and trifluralin) in aqueous solutions onto four adsorbents (sunflower seed shells, rice husk, composted sewage sludge and soil) was investigated. Pesticide determination was carried out using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. Maximum removal efficiency (73.9%) was reached using 1 g of rice husk and 50 mL of pesticide solution (200 μg L(-1)). The pseudo adsorption equilibrium was reached with 0.6 g organic residue, which was used in subsequent experiments. The pseudo-first-order, pseudo-second-order kinetics and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated. The first model was more suitable for the sorption of atrazine and alachlor while the pseudo-second-order best described endosulfan sulfate and trifluralin adsorption, which showed the fastest sorption rates. 4h was considered as the equilibrium time for determining adsorption isotherms. Experimental data were modeled by Langmuir and Freundlich models. In most of the studied cases both models can describe the adsorption process, although the Freundlich model was applicable in all cases. The sorption capacity increased with the hydrophobic character of the pesticides and decreased with their water solubility. Rice husk was revealed as the best adsorbent for three of the four studied pesticides (atrazine, alachlor and endosulfan sulfate), while better results were obtained with composted sewage sludge and sunflower seed shell for the removal of trifluralin. Although desorption percentages were not high (with the exception of alachlor, which reached a desorption rate of 57%), the Kfd values were lower than the Kf values for adsorption and all H values were below 100, indicating that the adsorption was weak. Copyright © 2014 Elsevier B.V. All rights reserved.

Integrated use of biomarkers and bioaccumulation data in Zebra mussel (Dreissena polymorpha) for site-specific quality assessment.

PubMed

Binelli, A; Ricciardi, F; Riva, C; Provini, A

2006-01-01

One of the useful biological tools for environmental management is the measurement of biomarkers whose changes are related to the exposure to chemicals or environmental stress. Since these responses might vary with different contaminants or depending on the pollutant concentration reached in the organism, the support of bioaccumulation data is needed to prevent false conclusions. In this study, several persistent organic pollutants -- 23 polychlorinated biphenyl (PCB) congeners, 11 polycyclic aromatic hydrocarbons (PAHs), six dichlorodiphenyltricholroethane (DDT) relatives, hexachlorobenzene (HCB), chlorpyrifos and its oxidized metabolite -- and some herbicides (lindane and the isomers alpha, beta, delta; terbutilazine; alachlor; metolachlor) were measured in the soft tissues of the freshwater mollusc Zebra mussel (Dreissena polymorpha) from 25 sampling sites in the Italian portions of the sub-alpine great lakes along with the measure of ethoxyresorufin dealkylation (EROD) and acetylcholinesterase (AChE) activity. The linkage between bioaccumulation and biomarker data allowed us to create site-specific environmental quality indexes towards man-made chemicals. This classification highlighted three different degrees of xenobiotic contamination of the Italian sub-alpine great lakes: a high water quality in Lake Lugano with negligible pollutant levels and no effects on enzyme activities, an homogeneous poor quality for Lakes Garda, Iseo and Como, and the presence of some xenobiotic point-sources in Lake Maggiore, whose ecological status could be jeopardized, also due to the heavy DDT contamination revealed since 1996.

Assessment of pesticide contamination in soil samples from an intensive horticulture area, using ultrasonic extraction and gas chromatography-mass spectrometry.

PubMed

Gonçalves, C; Alpendurada, M F

2005-03-15

In order to reduce the amount of sample to be collected and the time consumed in the analytical process, a broad range of analytes should be preferably considered in the same analytical procedure. A suitable methodology for pesticide residue analysis in soil samples was developed based on ultrasonic extraction (USE) and gas chromatography-mass spectrometry (GC-MS). For this study, different classes of pesticides were selected, both recent and old persistent molecules: parent compounds and degradation products, namely organochlorine, organophosphorous and pyrethroid insecticides, triazine and acetanilide herbicides and other miscellaneous pesticides. Pesticide residues could be detected in the low- to sub-ppb range (0.05-7.0mugkg(-1)) with good precision (7.5-20.5%, average 13.7% R.S.D.) and extraction efficiency (69-118%, average 88%) for the great majority of analytes. This methodology has been applied in a monitoring program of soil samples from an intensive horticulture area in Póvoa de Varzim, North of Portugal. The pesticides detected in four sampling programs (2001/2002) were the following: lindane, dieldrin, endosulfan, endosulfan sulfate, 4,4'-DDE, 4,4'-DDD, atrazine, desethylatrazine, alachlor, dimethoate, chlorpyrifos, pendimethalin, procymidone and chlorfenvinphos. Pesticide contamination was investigated at three depths and in different soil and crop types to assess the influence of soil characteristics and trends over time.

Leaching of Br-, metolachlor, alachlor, atrazine, deethylatrazine and deisopropylatrazine in clayey vadoze zone: a field scale experiment in north-east Greece.

PubMed

Vryzas, Zisis; Papadakis, Emmanuel Nikolaos; Papadopoulou-Mourkidou, E

2012-04-15

An extensive four-year research program has been carried out to explore and acquire knowledge about the fundamental agricultural practices and processes affecting the mobility and bioavailability of pesticides in soils under semi-arid Mediterranean conditions. Pesticide leaching was studied under field conditions at five different depths using suction cups. Monitoring of metolachlor, alachlor, atrazine, deethylatrazine (DEA), deisopropylatrazine (DIA), and bromide ions in soil water, as well as dye patterns made apparent the significant role of preferential flow to the mobility of the studied compounds. Irrespective to their adsorption capacities and degradation rates, atrazine, metolachlor and bromide ions were simultaneously detected to 160 cm depth. Following 40 mm irrigation, just after their application, both alachlor and atrazine were leached to 160 cm depth within 18 h, giving maximum concentrations of 211 and 199 μg L(-1), respectively. Metolachlor was also detected in all depth when its application was followed by a rainfall event (50 mm) two weeks after its application. The greatest concentrations of atrazine, alachlor and metolachlor in soil water were 1795, 1166 and 845 μg L(-1), respectively. The greatest concentrations of atrazine's degradation products (both DEA and DIA) appeared later in the season compared to the parent compound. Metolachlor exhibited the greatest persistence with concentrations up to 10 μg L(-1) appearing in soil water 18 months after its application. Brilliant blue application followed by 40 mm irrigation clearly depict multi-branching network of preferential flow paths allowing the fast flow of the dye down to 150 cm within 24 h. This network was created by soil cracks caused by shrinking of dry soils, earthworms and plant roots. Chromatographic flow of the stained soil solution was evident only in the upper 10-15 cm of soil. Copyright © 2012 Elsevier Ltd. All rights reserved.

Occurrence of selected pesticides and their metabolites in near-surface aquifers of the midwestern United States

USGS Publications Warehouse

Kolpin, D.W.; Michael, Thurman E.; Goolsby, D.A.

1996-01-01

The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to be found more frequently in groundwater than its parent compound. The metabolite alachlor ethanesulfonic acid (alachlor-ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid) was detected almost 10 times as frequently and at much higher concentrations than its parent compound alachlor (2-chloro-2‘,6‘-diethyl-N-(methoxymethyl)acetamide). The median detectable atrazine (2-chloro-4-ethylamino-6- isopropylamino-s-triazine) concentration was almost half that of atrazine residue (atrazine plus the two atrazine metabolites analyzed). Cyanazine amide [2-chloro-4-(1-carbamoyl-1-methylethylamino)-6-ethylamino-s-triazine] was detected almost twice as frequently as cyanazine (2-chloro-4-ethylamino-6-methylpropionitrileamino-s-triazine). Results show that information on pesticide metabolites is necessary to understand the environmental fate of pesticides. Consequently, if pesticide metabolites are not quantified, the effects of chemical use on groundwater quality would be substantially underestimated. Thus, continued research is needed to identify major degradation pathways for all pesticides and to develop analytical methods to determine their concentrations in water and other environmental media.

Comparative metabolism and elimination of acetanilide compounds by rat.

PubMed

Davison, K L; Larsen, G L; Feil, V J

1994-10-01

1. 14C-labelled propachlor, alachlor, butachlor, metolachlor, methoxypropachlor and some of their mercapturic acid pathway metabolites (MAP) were given to rat either by gavage or by perfusion into a renal artery. MAP metabolites were isolated from bile and urine. 2. Rat gavaged with propachlor and methoxypropachlor eliminated 14C mostly in urine, whereas rat gavaged with alachlor, butachlor and metolachlor eliminated 14C about equally divided between urine and faeces. When bile ducts were cannulated, the gavaged rat eliminated most of the 14C in bile for all compounds. The amount of 14C in bile from the propachlor-gavaged rat was less than that for the other acetanilides, with the difference being in the urine. 3. The mercapturic acid metabolites 2-methylsulphinyl-N-(1-methylhydroxyethyl)-N-phenylacetam ide and 2-methylsulphinyl-N-(1-methylmethoxyethyl)-N-phenylacetam ide were isolated from the urine and bile of the methoxypropachlor-gavaged rat. 4. Bile was the major route for 14C elimination when MAP metabolites of alachlor, butachlor and metolachlor were perfused into a renal artery. Urine was the major route for 14C elimination when MAP metabolites of propachlor and methoxypropachlor were perfused. Mercapturic acid conjugates were major metabolites in bile and urine when MAP metabolites were perfused. 5. We conclude that alkyl groups on the phenyl portion of the acetanilide causes biliary elimination to be favoured over urinary elimination.

Glutathione conjugation and contaminant transformation

USGS Publications Warehouse

Field, Jennifer A.; Thurman, E.M.

1996-01-01

The recent identification of a novel sulfonated metabolite of alachlor in groundwater and metolachlor in soil is likely the result of glutathione conjugation. Glutathione conjugation is an important biochemical reaction that leads, in the case of alachlor, to the formation of a rather difficult to detect, water-soluble, and therefore highly mobile, sulfonated metabolite. Research from weed science, toxicology, and biochemistry is discussed to support the hypothesis that glutathione conjugation is a potentially important detoxification pathway carried out by aquatic and terrestrial plants and soil microorganisms. A brief review of the biochemical basis for glutathione conjugation is presented. We recommend that multidisciplinary research focus on the occurrence and expression of glutathione and its attendant enzymes in plants and microorganisms, relationships between electrophilic substrate structure and enzyme activity, and the potential exploitation of plants and microorganisms that are competent in glutathione conjugation for phytoremediation and bioremediation.

Hydroxylamine Promoted Goethite Surface Fenton Degradation of Organic Pollutants.

PubMed

Hou, Xiaojing; Huang, Xiaopeng; Jia, Falong; Ai, Zhihui; Zhao, Jincai; Zhang, Lizhi

2017-05-02

In this study, we construct a surface Fenton system with hydroxylamine (NH 2 OH), goethite (α-FeOOH), and H 2 O 2 (α-FeOOH-HA/H 2 O 2 ) to degrade various organic pollutants including dyes (methyl orange, methylene blue, and rhodamine B), pesticides (pentachlorophenol, alachlor, and atrazine), and antibiotics (tetracycline, chloramphenicol, and lincomycin) at pH 5.0. In this surface Fenton system, the presence of NH 2 OH could greatly promote the H 2 O 2 decomposition on the α-FeOOH surface to produce ·OH without releasing any detectable iron ions during the alachlor degradation, which was different from some previously reported heterogeneous Fenton counterparts. Moreover, the ·OH generation rate constant of this surface Fenton system was 10 2 -10 4 times those of previous heterogeneous Fenton processes. The interaction between α-FeOOH and NH 2 OH was investigated with using attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory calculations. The effective degradation of organic pollutants in this surface Fenton system was ascribed to the efficient Fe(III)/Fe(II) cycle on the α-FeOOH surface promoted by NH 2 OH, which was confirmed by X-ray photoelectron spectroscopy analysis. The degradation intermediates and mineralization of alachlor in this surface Fenton system were then systematically investigated using total organic carbon and ion chromatography, liquid chromatography-mass spectrometry, and gas chromatography-mass spectrometry. This study offers a new strategy to degrade organic pollutants and also sheds light on the environmental effects of goethite.

Occurrence and Distribution of Pesticides in the St. Lucie River Watershed, South-Central Florida, 2000-01, Based on Enzyme-Linked Immunosorbent Assay (ELISA) Screening

USGS Publications Warehouse

Lietz, A.C.

2003-01-01

The St. Lucie River watershed is a valuable estuarine ecosystem and resource in south-central Florida. The watershed has undergone extensive changes over the last century because of anthropogenic activities. These activities have resulted in a complex urban and agricultural drainage network that facilitates the transport of contaminants, including pesticides, to the primary canals and then to the estuary. Historical data indicate that aquatic life criteria for selected pesticides have been exceeded. To address this concern, a reconnaissance was conducted to assess the occurrence and distribution of selected pesticides within the St. Lucie River watershed. Numerous water samples were collected from 37 sites among various land-use categories (urban/built-up, citrus, cropland/pastureland, and inte-grated). Samples were collected at inflow points to primary canals (C-23, C-24, and C-44) and at control structures along these canals from October 2000 to September 2001. Samples were screened for four pesticide classes (triazines, chloroacetanilides, chlorophenoxy compounds, and organophosphates) by using Enzyme-Linked Immunosorbent Assay (ELISA) screening. A temporal distribution of pesticides within the watershed was made based on samples collected at the integrated sites during different rainfall events between October 2000 and September 2001. Triazines were detected in 32 percent of the samples collected at the integrated sites. Chloroacetanilides were detected in 60 percent of the samples collected at the integrated sites, with most detections occurring at one site. Chlorophenoxy compounds were detected in 17 percent of the samples collected at the integrated sites. Organophosphates were detected in only one sample. A spatial distribution and range of concentration of pesticides at the 37 sampling sites in the watershed were determined among land-use categories. Triazine concentrations ranged from highest to lowest in the citrus, urban/built-up, and integrated areas, respectively. The highest median triazine concentration was found in the cropland/pastureland area. Chloroacetanilide concentra-tions ranged from highest to lowest in the citrus, integrated, urban/built-up, and cropland/pastureland areas, respectively. Chlorophenoxy compound concentrations ranged from highest to lowest in the urban/built-up, integrated, citrus, and cropland/pastureland areas, respectively. The maximum concentrations of triazines, chloroacetanilides, and chlorophenoxy compounds were 0.63, 1.0, and 14 micrograms per liter, respectively. Organophosphate was detected once at an integrated site at a concentration of 0.20 microgram per liter. Currently, the U.S. Environmental Protection Agency has no aquatic life guidelines for atrazine and metolachlor. However, assuming that all triazine and metolachlor concentrations from ELISA and gas chromatography/mass spectrometry (GC/MS) analyses were the result of atrazine and metolachlor detections, no concentrations exceeded the Canadian aquatic life guidelines for atrazine and metolachlor. One organophosphate detection (0.2 microgram per liter) did exceed the U.S. Environmental Protection Agency aquatic life guideline for chlorpyrifos. The deethylatrazine/atrazine ratio (DAR) is an important indicator of atrazine transport in the environment. The DAR ranged from 0.25 to 0.33, indicating that postapplication runoff was the most likely source of atrazine to the environment at the time of sampling. Deisopropylatrazine is a metabolite of atrazine and structurally similar compounds, such as simazine and cyanazine. The deisopropylatrazine/deethylatrazine ratio (D2R) is an indicator of nonpoint sources of deisopropylatrazine to the environment. The ratio ranged from 1 to 3 in this study, indicating simazine was an important source of deisopropylatrazine to the environment at the time of sampling, as opposed to atrazine alone. Confirmation analyses by GC/MS for triazines detected by ELISA indicated t

Evaluating Microtox as a tool for biodegradability assessment of partially treated solutions of pesticides using Fe3+ and TiO2 solar photo-assisted processes.

PubMed

Lapertot, Milena; Ebrahimi, Sirous; Oller, Isabel; Maldonado, Manuel I; Gernjak, Wolfgang; Malato, Sixto; Pulgarín, César

2008-03-01

To shorten phototreatment time is of major concern for the cost and energy benefits of the xenobiotics degradation performed by photocatalytic processes. Using photo-Fenton and TiO(2) phototreatments, partially photodegraded solutions of 6 separate pesticides (alachlor, atrazine, chlorfenvinphos, diuron, isoproturon and pentachlorophenol) were tested for biocompatibility, which was evaluated according to the Zahn-Wellens procedure. This study investigated if Microtox could be considered as a suitable global indicator capable of giving information on the evolution of biocompatibility of the water solution contaminated with organic pollutants during the phototreatment in order to promote biotreatment. The obtained results demonstrated that biodegradability increased significantly after short photo-Fenton treatment times for alachlor, diuron and pentachlorophenol. Uncertain results were obtained with atrazine and isoproturon. Microtox acute toxicity testing was shown to correctly represent dynamics and efficiency of phototreatment.

Ground-water quality in the Lake Champlain basin, New York, 2004

USGS Publications Warehouse

Nystrom, Elizabeth A.

2006-01-01

Water samples were collected from 11 public-supply wells and 11 private domestic wells in the Lake Champlain basin in New York during the fall of 2004 to characterize the chemical quality of ground water. Wells were selected for sampling based on location and focused on areas of greatest ground-water use. Samples were analyzed for 219 physical properties and constituents, including inorganic compounds, nutrients, metals, radionuclides, pesticides and pesticide degradates, volatile organic compounds, and bacteria. Sixty-eight constituents were detected at concentrations above laboratory reporting levels. The cation and anion with the highest median concentration were calcium (34.8 mg/L) bicarbonate (134 mg/L), respectively. The predominant nutrient was nitrate, which was detected in 14 (64 percent) of the 22 samples. The two metals with the highest median concentrations were iron (175 ?g/L) and strontium (124 ?g/L); concentrations of iron, manganese, aluminum, and zinc exceeded U.S. Environmental Protection Agency secondary drinking-water standards in one or more samples. Radon concentrations were less than 1,000 picocuries per liter (pCi/L) in most samples, but concentrations as high as 6,900 pCi/L were detected and, in eight samples, exceeded the U.S. Environmental Protection Agency proposed maximum contaminant level (300 pCi/L) for radon. The most frequently detected pesticides were degradates of the broadleaf herbicides metolachlor, alachlor, and atrazine. Volatile organic compounds were detected in only three samples; those that were detected typically were fuel oxygenates, such as methyl tert-butyl ether. Coliform bacteria were detected in four samples, two of which also tested positive for E. coli.

Water-quality assessment of the Kentucky River basin, Kentucky; nutrients, sediments, and pesticides in streams, 1987-90

USGS Publications Warehouse

Haag, K.H.; Porter, S.D.

1995-01-01

The U.S. Geological Survey investigated the water quality of the Kentucky River Basin in Kentucky as part of the National Water Quality Assessment program. Data collected during 1987-90 were used to describe the spatial and temporal variability of nutrients, suspended sediment, and pesticides in streams. Concentrations of phosphorus were signifi- cantly correlated with urban and agricultural land use. The high phosphorus content of Bluegrass Region soils was an important source of phosphorus in streams. At many sites in urban areas, all of the stream nitrogen load was attributable to wastewater- treatment-plant effluent. Tributary streams affected by agricultural sources of nutrients contained higher densities of phytoplankton than streams that drained forested areas. Data indicate that a consid- erable percentage of total nitrogen was transported as algal biomass during periods of low discharge. Average suspended-sediment concentrations for the study period were positively correlated with dis- charge. There was a downward trend in suspended- sediment concentrations downstream in the Kentucky River main stem during the study. Although a large amount of suspended sediment originates in the Eastern Coal Field Region, contributions of suspended sediment from the Red River and other tributary streams of the Knobs Region also are important. The most frequently detected herbicides in water samples were atrazine, 2,4-D, alachlor, metolachlor, and dicamba. Diazinon, malathion, and parathion were the most frequently detected organo- phosphate insecticides in water samples. Detectable concentrations of aldrin, chlordane, DDT, DDE, dieldrin, endrin, endosulfan, heptachlor, heptachlor epoxide, and lindane were found in streambed- sediment samples.

Fate and transport of pesticides in the ground water systems of southwest Georgia, 1993-2005

USGS Publications Warehouse

Dalton, M.S.; Frick, E.A.

2008-01-01

Modern agricultural practices in the United States have resulted in nearly unrivaled efficiency and productivity. Unfortunately, there is also the potential for release of these compounds to the environment and consequent adverse affects on wildlife and human populations. Since 1993, the National Water-Quality Assessment (NAWQA) program of the U.S. Geological Survey has evaluated water quality in agricultural areas to address these concerns. The objective of this study is to evaluate trends in pesticide concentrations from 1993-2005 in the surficial and Upper Floridan aquifers of southwest Georgia using pesticide and pesticide degradate data collected for the NAWQA program. There were six compounds - five herbicides and one degradate - that were detected in more than 20% of samples: atrazine, deethylatrazine (DEA), metolachlor, alachlor, floumeturon, and tebuthiuron. Of the 128 wells sampled during the study, only eight wells had pesticide concentrations that either increased (7) or decreased (1) on a decadal time scale. Most of the significant trends were increasing concentrations of pesticides in older water; median pesticide concentrations did not differ between the surficial and Upper Floridan aquifers from 1993 and 2005. Deethylatrazine, in the Upper Floridan aquifer, was the only compound that had a significant change (increase) in concentration during the study. The limited number of wells with increases in pesticide concentrations suggest that ground-water sources of these compounds are not increasing in concentration over the time scale represented in this study. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Pesticide use and risk of end-stage renal disease among licensed pesticide applicators in the Agricultural Health Study

PubMed Central

Lebov, Jill F.; Engel, Lawrence S.; Richardson, David; Hogan, Susan L.; Hoppin, Jane A.; Sandler, Dale P.

2017-01-01

Objectives Experimental studies suggest a relationship between pesticide exposure and renal impairment, but epidemiological evidence is limited. We evaluated the association between exposure to 41 specific pesticides and end-stage renal disease (ESRD) incidence in the Agricultural Health Study (AHS), a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. Methods Via linkage to the United States Renal Data System, we identified 320 ESRD cases diagnosed between enrollment (1993-1997) and December 2011 among 55,580 male licensed pesticide applicators. Participants provided pesticide use information via self-administered questionnaires. Lifetime pesticide use was defined as the product of duration and frequency of use and then modified by an intensity factor to account for differences in pesticide application practices. Cox proportional hazards models, adjusted for age and state, were used to estimate associations between ESRD and: 1) ordinal categories of intensity-weighted lifetime use of 41 pesticides, 2) poisoning and high-level pesticide exposures, and 3) pesticide exposure resulting in a medical visit or hospitalization. Results Positive exposure-response trends were observed for the herbicides alachlor, atrazine, metolachlor, paraquat, and pendimethalin, and the insecticide chlordane. More than one medical visit due to pesticide use (HR = 2.13; 95% CI: 1.17, 3.89) and hospitalization due to pesticide use (HR = 3.05; 95% CI: 1.67, 5.58) were significantly associated with ESRD. Conclusions Our findings support an association between ESRD and chronic exposure to specific pesticides and suggest pesticide exposures resulting in medical visits may increase the risk of ESRD. PMID:26177651

CURRENT-USE PESTICIDES: ASSESSING EXPOSURE AND SPERMATOXICITY

EPA Science Inventory

We recently reported that higher levels of urinary metabolite (mercapturates) of the current-use pesticides alachlor, atrazine and diazinon were significantly associated with decreased semen quality in fertile men from mid-Missouri. The primary goal of this stud...

Four-year advanced monitoring program of polar pesticides in groundwater of Catalonia (NE-Spain).

PubMed

Köck-Schulmeyer, Marianne; Ginebreda, Antoni; Postigo, Cristina; Garrido, Teresa; Fraile, Josep; López de Alda, Miren; Barceló, Damià

2014-02-01

Pesticide contamination of groundwater is of paramount importance because it is the most sensitive and the largest body of freshwater in the European Union. In this paper, an isotopic dilution method based on on-line solid phase extraction-liquid chromatography (electrospray)-tandem mass spectrometry (SPE-LC(ESI)-MS/MS) was used for the analysis of 22 pesticides in groundwater. Results were evaluated from monitoring 112 wells and piezometers coming from 29 different aquifers located in 18 ground water bodies (GWBs), from Catalonia, Spain, for 4 years as part of the surveillance and operational monitoring programs conducted by the Catalan Water Agency. The analytical method developed allows the determination of the target pesticides (6 triazines, 4 phenylureas, 4 organophosphorous, 1 anilide, 2 chloroacetanilides, 1 thiocarbamate, and 4 acid herbicides) in groundwater with good sensitivity (limits of detection <5 ng/L), accuracy (relative recoveries between 85 and 116%, except for molinate), and repeatability (RSD<23%), and in a fully automated way. The most ubiquitous compounds were simazine, atrazine, desethylatrazine and diuron. Direct relation between frequency of detection of each target compound and Groundwater Ubiquity Score index (GUS index) is observed. Desethylatrazine and deisopropylatrazine, metabolites of atrazine and simazine, respectively, presented the highest mean concentrations. Compounds detected in less than 5% of the samples were cyanazine, molinate, fenitrothion and mecoprop. According to the Directive 2006/118/EC, 13 pesticides have individual values above the requested limits (desethylatrazine, atrazine and terbuthylazine lead the list) and 14 samples have total pesticide levels above 500 ng/L. The GWB with the highest levels of total pesticides is located in Lleida (NE-Spain), with 9 samples showing total pesticide levels above 500 ng/L. Several factors such as regulation of the use of pesticides, type of activities in the area, and irrigation were discussed in relation to the observed levels of pesticides. © 2013.

Relation of pesticide concentrations to season, streamflow, and land use in seven New Jersey streams

USGS Publications Warehouse

Reiser, Robert G.

1999-01-01

The presence and variability of pesticides in seven New Jersey streams was documented by analyzing 146 samples collected from the streams from April 1996 through June 1998. The samples were analyzed for 85 pesticides, including 50 herbicides, 28 insecticides, and 7 degradation products, at method detection limits that ranged from 0.001 to 0.018 μg/L (micrograms per liter). Pesticides were frequently detected; however, concentrations were generally low. The pesticides most frequently detected were atrazine, in 97 percent of the samples; prometon, 96 percent; metolachlor, 95 percent; desethyl-atrazine, 91 percent; simazine, 88 percent; diazinon, 58 percent; alachlor, 56 percent; and carbaryl, 54 percent. Detection frequencies were highest during the growing season (April-September). At least one pesticide was detected in all but one of these samples, and 49 percent of the samples contained 9 or more pesticides. The numbers of pesticides detected at a given site ranged from 13 to 29. Ten pesticides were detected at concentrations that exceeded established water-quality criteria. Thirty-one of these detections were in samples collected during the growing season and one during the nongrowing season. The pesticides that exceeded the U.S. Environmental Protection Agency (USEPA) maximum contaminant level for drinking water were atrazine, which exceeded 3 μg/L in four samples, and alachlor, 2 μg/L in two samples. Cyanazine exceeded the USEPA liftime health advisory level (HAL) of 1 μg/L in two samples. These eight detections occurred during runoff shortly after spring pesticide applications and represent a potential threat to municipal water supplies in the Raritan River basin. Concentrations of chlorpyrifos, chlorthalonil, diazinon, ethyl-parathion, and methyl-azinphos exceeded the chronic life criteria for the protection of aquatic life (ACQR) in 20 samples at four sites during the growing season. Dieldrin was detected in four samples and DDE in two samples at concentrations that exceeded New Jersey Department of Environmental Protection (NJDEP) human health criteria. Individual and total-pesticide concentrations and total numbers of pesticides detected in the samples varied with season and flow conditions. Median and maximum concentrations of most of the pesticides were highest during runoff in the growing season. Pesticide concentrations were typically lower and less variable in the nongrowing season than in the growing season, regardless of changes in hydrologic conditions; however, median concentrations of most pesticides were slightly lower during runoff than during base flow. The median total-pesticide concentration and median total number of pesticides detected were highest and most variable in runoff samples in the growing season. In the nongrowing season, the median total-pesticide concentration was lowest in runoff samples and least variable during base-flow conditions. Median total numbers of pesticides were lowest and least varibale in the nongrowing season during base-flow conditions at most sites. The highest total-pesticide concentrations were detected in samples from the two small agricultural basins (greater than 25 percent of land use is agricultural) during runoff in late spring and early summer. In general, insecticides were detected more frequently and in greater concentrations at urban sites. Concentrations of agricultural herbicides generally decreased with increasing flow at the four sites with less than 10 percent agriculture land use and increased with increasing flow at the three sites with more than 25 percent agricultural land use. Most of the pesticides that correlated positively with streamflow were detected at sites where land use in the basin would indicate the use of those particular pesticides. Most of the pesticides that correlated negatively with streamflow were present at the site in the Coastal Plain or at sites in which the land use in the basin would not indicate heavy u

Simultaneous LC determination of paracetamol and related compounds in pharmaceutical formulations using a carbon-based column.

PubMed

Monser, Lotfi; Darghouth, Frida

2002-03-01

A simple, rapid and convenient high performance liquid chromatographic method, which permits the simultaneous determination of paracetamol, 4-aminophenol and 4-chloracetanilide in pharmaceutical preparation has been developed. The chromatographic separation was achieved on porous graphitized carbon (PGC) column using an isocratic mixture of 80/20 (v/v) acetonitrile/0.05 M potassium phosphate buffer (pH 5.5) and ultraviolet detection at 244 nm. Correlation coefficient for calibration curves in the ranges 1-50 microg ml(-1) for paracetamol and 5-40 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide were >0.99. The sensitivity of detection is 0.1 microg ml(-1) for paracetamol and 0.5 microg ml(-1) for 4-aminophenol and 4-chloroacetanilide. The proposed liquid chromatographic method was successfully applied to the analysis of commercially available paracetamol dosage forms with recoveries of 98-103%. It is suggested that the proposed method should be used for routine quality control and dosage form assay of paracetamol in pharmaceutical preparations. The chromatographic behaviour of the three compounds was examined under variable mobile phase compositions and pH, the results revealed that selectivity was dependent on the organic solvent and pH used. The retention selectivity of these compounds on PGC was compared with those of octadecylsilica (ODS) packing materials in reversed phase liquid chromatography. The ODS column gave little separation for the degradation product (4-aminophenol) from paracetamol, whereas PGC column provides better separation in much shorter time.

New insights into the interactions between cork chemical components and pesticides. The contribution of π-π interactions, hydrogen bonding and hydrophobic effect.

PubMed

Olivella, M À; Bazzicalupi, C; Bianchi, A; Fiol, N; Villaescusa, I

2015-01-01

The role of chemical components of cork in the sorption of several pesticides has been investigated. For this purpose raw cork and three cork extracted fractions (i.e. cork free of aliphatic extractives, cork free of all extractives and cork free of all extractives and suberin) were used as sorbent of three ionic pesticides (propazine, 2,4-dichlorophenoxy acetic acid (2,4-D) and alachlor) and five non-ionic pesticides (chlorpyrifos, isoproturon, metamitron, methomyl and oxamyl) with a logKow within the range -0.47 to 4.92. The effect of cations on the ionic pesticides, propazine and 2,4-D sorption was also analyzed. Results indicated that the highest yields were obtained for chlorpyrifos and alachlor sorption onto raw cork (>55%). After removal of aliphatic extractives sorption of all pesticides increased that ranged from 3% for propazine to 31% for alachlor. In contrast, removal of phenolic extractives caused a sorption decrease. Low sorption yields were obtained for hydrophobic pesticides such as metamitron, oxamyl and methomyl (<11%) by using all cork fractions and extremely low when using raw cork (<1%). FTIR analysis was useful to indicate that lignin moieties were the main components involved on the sorption process. Modelling calculations evidenced that π-stacking interactions with the aromatic groups of lignin play a major role in determining the adsorption properties of cork toward aromatic pesticides. Results presented in this paper gain insights into the cork affinities for pesticides and the interactions involved in the sorption process and also enables to envisage sorption affinity of cork for other organic pollutants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Input dynamics of pesticide transformation products into surface water

NASA Astrophysics Data System (ADS)

Kern, Susanne; Singer, Heinz; Hollender, Juliane; Schwarzenbach, René P.; Fenner, Kathrin

2010-05-01

Some pesticide transformation products have been observed to occur in higher concentrations and more frequently than the parent active pesticide in surface water and groundwater. These products are often more mobile and sometimes more stable than the parent pesticide. If they also represent the major product into which the parent substance is transformed, these transformation products may dominate observed pesticide occurrences in surface water and groundwater. Their potential contribution to the overall risk to the aquatic environment caused by the use of the parent pesticide should therefore not be neglected in chemical risk and water quality assessments. The same is true for transformation products of other compound classes that might reach the soil environment, such as veterinary pharmaceuticals. However, the fate and input pathways of transformation products of soil-applied chemicals into surface water are not yet well understood, which largely prevents their appropriate inclusion into chemical risk and water quality assessments. Here, we studied whether prioritization methods based on available environmental fate data from pesticide registration dossiers in combination with basic fate models could help identify transformation products which can be found in relevant concentrations in surface and groundwater and which should therefore be included into monitoring programs. A three-box steady state model containing air, soil, and surface water compartments was used to predict relative inputs of pesticide transformation products into surface waters based on their physico-chemical and environmental fate properties. The model predictions were compared to monitoring data from a small Swiss river located in an intensely agricultural catchment (90 km2) which was flow-proportionally sampled from May to October 2008 and screened for 74 pesticides as well as 50 corresponding transformation products. Sampling mainly occurred during high discharge, but additional samples during baseflow conditions were also taken. The analytical measurements included solid phase extraction, liquid chromatography and high resolution mass spectrometry (SPE-LC-HR-MS/MS). Quantification was achieved using reference standards and internal standards. Besides the well-known transformation products of triazine and chloroacetanilide herbicides, transformation products of other compound classes such as azoxystrobin acid (from azoxystrobin, strobilurin fungicide), chloridazon-desphenyl and chloridazon-methyl-desphenyl (from chloridazon, pyridazinone herbicide), and metamitron-desamino (from metamitron, triazinone herbicide) were analyzed in surface water. For a selection of widely used pesticides in the catchment, modelled ratios of transformation product versus parent pesticide concentrations were compared to the measured concentration ratios in the river for the application period and for two 2-month periods following application. Concentration ratios agreed within a factor of 10 for all pairs of parent pesticides and transformation products, and for all seasons, with a single exception. The ratio of chloridazon-desphenyl to chloridazon was under-predicted by a factor of approximately 20. The data revealed that chloridazon-desphenyl was also found in elevated concentrations in all baseflow samples, indicating its presence in the groundwater component of the catchment. The same was true for other transformation products (e.g., metamitron-desamino, chloridazon-methly-desphenyl, metolachlor-ESA), but to a lesser degree. Based on baseflow separation of the hydrograph, the concentration ratio estimation model was supplemented with an additional baseflow component. The concentrations in the baseflow component were estimated with a simple leaching relationship that was compared against measured baseflow concentrations and groundwater findings in Switzerland. The final model yielded good agreement for all compounds and is therefore deemed suitable for prioritization of transformation products with a relevant exposure potential. It also clearly indicated the contribution of groundwater to the overall occurrence of pesticides and their transformation products in Swiss surface waters.

HPLC-NMR INVESTIGATION OF THE ISOMERIZATION OF ALACHLOR-ETHANE SULFONIC ACID. (R829008)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

ALACHLOR AND ATRAZINE BIODEGRADATION UNDER DENITRIFYING ELECTRON ACCEPTOR CONDITIONS. (R825549C037)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Detection of Pesticides and Pesticide Metabolites Using the Cross Reactivity of Enzyme Immunoassays

USGS Publications Warehouse

Thurman, E.M.; Aga, D.S.

2001-01-01

Enzyme immunoassay is an important environmental analysis method that may be used to identify many pesticide analytes in water samples. Because of similarities in chemical structure between various members of a pesticide class, there often may be an unwanted response that is characterized by a percentage of cross reactivity. Also, there may be cross reactivity caused by degradation products of the target analyte that may be present in the sample. In this paper, the concept of cross reactivity caused by degradation products or by nontarget analytes is explored as a tool for identification of metabolites or structurally similar compounds not previously known to be present in water samples. Two examples are examined in this paper from various water quality studies. They are alachlor and its metabolite, alachlor ethane sulfonic acid, and atrazine and its class members, prometryn and propazine. A method for using cross reactivity for the detection of these compounds is explained in this paper.

EVALUATION OF GENETIC DAMAGE IN FISH EXPOSED TO PESTICIDES IN FIELD AQUATIC MICROCOSMS

EPA Science Inventory

Single cell gel electrophoresis (SCG) and micronucleus (MN) assays were used to measure DNA strand breaks and chromosomal damage in fish blood erythrocytes as biological indicators of exposure to alachlor and atrazine in a surrogate aquatic ecosystem. Caged common carp (Cyprinus...

Pesticide use and risk of end-stage renal disease among licensed pesticide applicators in the Agricultural Health Study.

PubMed

Lebov, Jill F; Engel, Lawrence S; Richardson, David; Hogan, Susan L; Hoppin, Jane A; Sandler, Dale P

2016-01-01

Experimental studies suggest a relationship between pesticide exposure and renal impairment, but epidemiological evidence is limited. We evaluated the association between exposure to 39 specific pesticides and end-stage renal disease (ESRD) incidence in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. Via linkage to the US Renal Data System, we identified 320 ESRD cases diagnosed between enrolment (1993-1997) and December 2011 among 55 580 male licensed pesticide applicators. Participants provided information on use of pesticides via self-administered questionnaires. Lifetime pesticide use was defined as the product of duration and frequency of use and then modified by an intensity factor to account for differences in pesticide application practices. Cox proportional hazards models, adjusted for age and state, were used to estimate associations between ESRD and: (1) ordinal categories of intensity-weighted lifetime use of 39 pesticides, (2) poisoning and high-level pesticide exposures and (3) pesticide exposure resulting in a medical visit or hospitalisation. Positive exposure-response trends were observed for the herbicides alachlor, atrazine, metolachlor, paraquat, and pendimethalin, and the insecticide permethrin. More than one medical visit due to pesticide use (HR=2.13; 95% CI 1.17 to 3.89) and hospitalisation due to pesticide use (HR=3.05; 95% CI 1.67 to 5.58) were significantly associated with ESRD. Our findings support an association between ESRD and chronic exposure to specific pesticides, and suggest pesticide exposures resulting in medical visits may increase the risk of ESRD. Clinicaltrials.gov NCT00352924. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Water-quality assessment of the Kentucky River basin, Kentucky; results of investigations of surface-water quality, 1987-90

USGS Publications Warehouse

Haag, K.H.; Garcia, Rene; Jarrett, G.L.; Porter, S.D.

1995-01-01

The U.S. Geological Survey investigated the water quality of the Kentucky River Basin in Kentucky as part of the National Water-Quality Assessment program. Data collected during 1987-90 were used to describe the spatial and temporal variability of water-quality constituents including metals and trace elements, nutrients, sediments, pesticides, dissolved oxygen, and fecal-coliform bacteria. Oil-production activities were the source of barium, bromide, chloride, magnesium, and sodium in several watersheds. High concentrations of aluminum, iron, and zinc were related to surface mining in the Eastern Coal Field Region. High concentrations of lead and zinc occurred in streambed sediments in urban areas, whereas concentrations of arsenic, strontium, and uranium were associated with natural geologic sources. Concentrations of phosphorus were significantly correlated with urban and agricultural land use. The high phosphorus content of Bluegrass Region soils was an important source of phosphorus in streams. At many sites in urban areas, most of the stream nitrogen load was attributable to wastewater-treatment-plant effluent. Average suspended-sediment concentrations were positively correlated with discharge. There was a downward trend in suspended-sediment concentrations downstream in the Kentucky River main stem during the study. The most frequently detected herbicides in water samples were atrazine, 2,4-D, alachlor, metolachlor, and dicamba. Diazinon, malathion, and parathion were the most frequently detected organophosphate insecticides in water samples. Detectable concentrations of aldrin, chlordane, DDT, DDE, dieldrin, endrin, endosulfan, heptachlor, and lindane were found in streambed-sediment samples. Dissolved-oxygen concentrations were sometimes below the minimum concentration needed to sustain aquatic life. At some sites, high concentrations of fecal-indicator bacteria were found and water samples did not meet sanitary water-quality criteria.

Pesticides in shallow groundwater in the Delmarva Peninsula

USGS Publications Warehouse

Koterba, M.T.; Banks, W.S.L.; Shedlock, R.J.

1993-01-01

A regional study of the areal and depth distribution of pesticides in shallow groundwater in the Delmarva Peninsula of Delaware, Maryland, and Virginia was done to (i) relate the pesticides detected to landscape and shallow subsurface features, and (ii) evaluate aquifer vulnerability and the potential contamination of drinking-water supplies. Water samples collected at 100 wells from 1988 to 1990 were analyzed for concentrations of 36 pesticides, four metabolites, and other constituents. The most commonly detected residues were atrazine, cyanazine, simazine, alachlor, metolachlor, and dicamba. Concentrations were low; few exceeded 3 ??g L-1. Most detections correlate with the intensive use of these herbicides in three widely distributed and commonly rotated crops-corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and small grain-particularly if grown in well- drained soils. Most detections occurred in samples collected from shallow wells screened within 10 m of the overlying water table. The shallow depth distribution of most residues is consistent with their suspected history of use (ca. 20 yr), and patterns in shallow groundwater flow in the surficial aquifer in the study area. The areal and depth distributions of detectable residues in groundwater did not correlate with a vulnerability index, nor any of the component scores developed to estimate that index using the DRASTIC method. The shallow depth of most detections also indicates why few samples from water-supply wells in this study had measurable concentrations of pesticides; most supply wells are deeper than 10 m below the water table. The low number of contaminated samples from supply wells implies that deep groundwater currently (1992) used for drinking generally does not contain detectable pesticide residues.

Identification of new human pregnane X receptor ligands among pesticides using a stable reporter cell system.

PubMed

Lemaire, Géraldine; Mnif, Wissem; Pascussi, Jean-Marc; Pillon, Arnaud; Rabenoelina, Fanja; Fenet, Hélène; Gomez, Elena; Casellas, Claude; Nicolas, Jean-Claude; Cavaillès, Vincent; Duchesne, Marie-Josèphe; Balaguer, Patrick

2006-06-01

Pregnane X receptor (PXR, NR1I2) is activated by various chemically unrelated compounds, including environmental pollutants and drugs. We proceeded here to in vitro screening of 28 pesticides with a new reporter system that detects human pregnane X receptor (hPXR) activators. The cell line was obtained by a two-step stable transfection of cervical cancer HeLa cells. The first transfected cell line, HG5LN, contained an integrated luciferase reporter gene under the control of a GAL4 yeast transcription factor-binding site. The second cell line HGPXR was derived from HG5LN and stably expressed hPXR ligand-binding domain fused to GAL4 DNA-binding domain (DBD). The HG5LN cells were used as a control to detect nonspecific activities. Pesticides from various chemical classes were demonstrated, for the first time, to be hPXR activators: (1) herbicides: pretilachlor, metolachlor, and alachlor chloracetanilides, oxadiazon oxiconazole, and isoproturon urea; (2) fungicides: bupirimate and fenarimol pyrimidines, propiconazole, fenbuconazole, prochloraz conazoles, and imazalil triazole; and (3) insecticides: toxaphene organochlorine, permethrin pyrethroid, fipronil pyrazole, and diflubenzuron urea. Pretilachlor, metolachlor, bupirimate, and oxadiazon had an affinity for hPXR equal to or greater than the positive control rifampicin. Some of the newly identified hPXR activators were also checked for their ability to induce cytochrome P450 3A4 expression in a primary culture of human hepatocytes. HGPXR, with HG5LN as a reference, was grafted onto nude mice to assess compound bioavailability through in vivo quantification of hPXR activation. Altogether, our data indicate that HGPXR cells are an efficient tool for identifying hPXR ligands and establishing pesticides as hPXR activators.

Hydrogeology and water quality of the Pepacton Reservoir Watershed in southeastern New York. Part 1. Concentrations of pesticides and their degradates in stream baseflow, 2000-2001

USGS Publications Warehouse

Phillips, Patrick J.; Heisig, Paul M.

2004-01-01

Baseflow samples were collected from 20 small streams in the Pepacton Reservoir watershed in Delaware County, N.Y., from December 2000 through November 2001 as part of an investigation to define the occurrence of pesticides in shallow ground water in watersheds containing either a recent (2001) corn crop, a previous (1993-94) corn crop, or no history of row-crop cultivation. Baseflow water quality was assumed to represent the chemical quality of shallow ground water within the drainage area above each sampling site.Baseflow samples were analyzed for 57 pesticides and pesticide degradates. Three herbicides (atrazine, metolachlor and simazine) and three herbicide degradates (alachlor ESA [ethanesulfonic acid], deethylatrazine, and metolachlor ESA) were detected, but no concentrations exceeded any Federal or State water-quality criteria, and the maximum concentrations of all compounds except metolachlor ESA were less than 0.10 microgram per liter. The most frequently detected compounds (atrazine, metolachlor, deethylatrazine and metolachlor ESA) are either those typically used on corn crops, or those whose parent compounds are commonly used on corn crops and have been detected in streams that drain row-crop settings elsewhere in New York State. The pesticide and pesticide-degradate concentrations in baseflow samples collected in December 2000 and July 2001 samples generally corresponded to the amount of cornfield acreage in each watershed in 2001.The types of pesticides detected, and their median concentrations, were similar to those noted in two previous ground-water studies in row-crop areas elsewhere in upstate New York. Also the SAM ratios (ratio of metolachlor ESA concentration to metolachlor concentration) for the Pepacton samples were similar to those for ground-water samples from other agricultural settings in upstate New York, but were significantly higher than that for stormflow and baseflow samples collected in 1997-98 from Canajoharie Creek, an upstate stream that drains row-crop farmland. These comparisons confirm that the baseflow samples were derived from, and were representative of, ground water in their respective watersheds. Late-summer decreases in atrazine and deethylatrazine concentrations at a site where corn was grown in 2001 may have resulted from the seasonally dry conditions and the accompanying decrease in ground-water discharge from the upper-most part of the surficial aquifer system to streams. The lack of a similar decrease in metolachlor ESA concentrations during this period may reflect the transport of metolachlor ESA to deeper parts of the surficial aquifer that continued to discharge to streams during the dry period.

Pesticides and pesticide degradates in the East Fork Little Miami River and William H. Harsha Lake, southwestern Ohio, 1999-2000

USGS Publications Warehouse

Funk, Jason M.; Reutter, David C.; Rowe, Gary L.

2003-01-01

In 1999 and 2000, the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program conducted a national pilot study of pesticides and degradates in drinking-water supplies, in cooperation with the U.S. Environmental Protection Agency (USEPA). William H. Harsha Lake, which provides drinking water for several thousand people in southwestern Ohio, was selected as one of the drinking-water supplies for this study. East Fork Little Miami River is the main source of water to Harsha Lake and drains a predominantly agricultural basin. Samples were collected from the East Fork Little Miami River upstream from Harsha Lake, at the drinking-water intake at Harsha Lake, at the outfall just below Harsha Lake, and from treated water at the Bob McEwen Treatment Plant. These samples were analyzed using standardized methods developed for the NAWQA Program. In all, 42 pesticide compounds (24 herbicides, 4 insecticides, 1 fungicide, and 13 degradates) were detected at least once in samples collected during this study. No compound in the treated water samples exceeded any drinking-water standard, although atrazine concentrations in untreated water exceeded the USEPA Maximum Contaminant Level (MCL) for drinking water (3 ?g/L) on four occasions. At least eight compounds were detected with greater than 60 percent frequency at each sampling location. Herbicides, such as atrazine, alachlor, acetochlor, cyanazine, metolachlor, and simazine, were detected most frequently. Rainfall affected the pesticide concentrations in surface waters of the East Fork Little Miami River Basin. Drought conditions from May through November 1999 led to lower streamflow and pesticide concentrations throughout southwestern Ohio. More normal climate conditions during 2000 resulted in higher streamflows and seasonally higher concentrations in the East Fork Little Miami River and Harsha Lake for some pesticides Comparison of pesticide concentrations in untreated lake water and treated drinking water supplied by the Bob McEwen Treatment Plant suggests that treatment processes employed by the plant (chlorination, activated carbon) reduced pesticide concentrations to levels well below USEPA drinking-water standards. In particular, the percentage of pesticides remaining in treated water samples decreased significantly for several frequently occurring pesticides when the plant replaced the use of powdered activated carbon with granular activated carbon in November 1999. For example, the median percentage of atrazine remaining after treatment that included powdered activated carbon was 63 percent, whereas the median percentage of atrazine remaining after the switch to granular activated carbon was 2.4 percent.

77 FR 38523 - Expedited Approval of Alternative Test Procedures for the Analysis of Contaminants Under the Safe...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-28

... of semivolatile organic compounds in finished drinking water. The method analytes are extracted and... semivolatile organic contaminants: Alachlor, atrazine, polychlorinated biphenyls (PCBs), benzo[a]pyrene... approved EPA Method 525.2, Revision 2.0 for each of the 17 regulated semivolatile organic contaminants. EPA...

Precision Herbicide Application Technologies To Decrease Herbicide Losses in Furrow Irrigation Outflows in a Northeastern Australian Cropping System.

PubMed

Davis, Aaron M; Pradolin, Jordan

2016-05-25

This study compared water quality benefits of using precision herbicide application technologies in relation to traditional spraying approaches across several pre- and postemergent herbicides in furrow-irrigated canefarming systems. The use of shielded sprayers (herbicide banding) provided herbicide load reductions extending substantially beyond simple proportionate decreases in amount of active herbicide ingredient applied to paddocks. These reductions were due largely to the extra management control available to irrigating growers in relation to where both herbicides and irrigation water can be applied to paddocks, coupled with knowledge of herbicide toxicological and physicochemical properties. Despite more complex herbicide mixtures being applied in banded practices, banding provided capacity for greatly reduced environmental toxicity in off-paddock losses. Similar toxicological and loss profiles of alternative herbicides relative to recently regulated pre-emergent herbicides highlight the need for a carefully considered approach to integrating alternative herbicides into improved pest management.

CADDIS Volume 2. Sources, Stressors and Responses: Herbicides

EPA Pesticide Factsheets

Introduction to the herbicides module, when to list herbicides as a candidate cause, ways to measure herbicides, simple and detailed conceptual diagrams for herbicides, herbicides module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Herbicides - Detailed Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the herbicides module, when to list herbicides as a candidate cause, ways to measure herbicides, simple and detailed conceptual diagrams for herbicides, herbicides module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Herbicides - Simple Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the herbicides module, when to list herbicides as a candidate cause, ways to measure herbicides, simple and detailed conceptual diagrams for herbicides, herbicides module references and literature reviews.

A urinary metabonomics analysis of long-term effect of acetochlor exposure on rats by ultra-performance liquid chromatography/mass spectrometry.

PubMed

Li, Longxue; Wang, Maoqing; Chen, Shuhong; Zhao, Wei; Zhao, Yue; Wang, Xu; Zhang, Yang

2016-03-01

The study was to assess the long-term toxic effects of acetochlor on rats. Two different doses (42.96 and 107.4 mg/kg body weight/day) of acetochlor were administered to Wistar rats through their food for over 24 weeks. Rat urine samples were collected at two time-points for the measurements of the metabonomics profiles with ultra-performance liquid chromatography-mass spectrometry (UPLC-MSMS). The results of clinical chemistry and histopathology suggested that long-term use of acetochlor in rats caused liver and kidney damage, and dysfunction of antioxidant system. The urinary metabonomics analysis indicated that the high and low-dose exposure of acetochlor could cause alterations of these metabonomics in urine in the rat. Significant changes of the levels of hippuric acid (0.403-fold decrease), citric acid (0.430-fold decrease), pantothenic acid (0.486-fold decrease), uracil (0.419-fold decrease), β-Alanine (0.325-fold decrease), nonanedioic acid (0.445-fold decrease), L-tyrosine (0.410-fold decrease), D-glucuronic acid (8.389-fold increase) and 2-ethyl-6-methyl-N-methyl-2-chloro-acetanilide in urine were observed. In addition, it may interfere with the fatty acid synthesis, the pyrimidine degradation and pantothenate biosynthesis. The level of 2-ethyl-6-methyl-N-methyl-2-chloro-acetanilide is detected in all treated groups which is not found in the control groups, indicating which can be used as an early, sensitive marker of acetochlor exposure in rat. This study illustrates the important utility of metabonomics approaches to understand the toxicity of long-term exposure of acetochlor. Copyright © 2015. Published by Elsevier Inc.

Quality of water on the Prairie Band Potawatomi Reservation, northeastern Kansas, February 1999 through February 2001

USGS Publications Warehouse

Trombley, T.J.

2001-01-01

Water-quality samples were collected from 20 surface-water sites and 7 ground-water sites across the Prairie Band Potawatomi Reservation in northeastern Kansas as part of a water-quality study begun in 1996. Water quality is a very important consideration for the tribe. Three creeks draining the reservation, Soldier, Little Soldier, and South Cedar Creeks, are important tribal resources used for maintaining subsistence fishing and hunting needs for tribal members. Samples were collected twice during June 1999 and June 2000 at all 20 surface-water sites after herbicide application, and nine quarterly samples were collected at 5 of the 20 sampling sites from February 1999 through February 2001. Samples were collected once at six wells and twice at one well from September through December 2000. Surface-water-quality constituents analyzed included nutrients, pesticides, and bacteria. In addition to nutrients, pesticides, and bacteria, ground-water constituents analyzed included major dissolved ions, arsenic, boron, and dissolved iron and manganese. The median nitrite plus nitrate concentration was 0.376 mg/L (milligram per liter) for 81 surface-water samples, and the maximum concentration was 4.18 mg/L as nitrogen, which is less than one-half the U.S. Environmental Protection Agency's Maximum Contaminant Level (MCL) for drinking water of 10 mg/L as nitrogen. Fifty-one of the 81 surface-water-quality samples exceeded the U.S. Environmental Protection Agency's recommended goal for total phosphorus of 0.10 mg/L for the protection of aquatic life. Triazine concentrations in 26 surface-water-quality samples collected during May and June 1999 and 2000 exceeded 3.0 ?g/L (micrograms per liter), the Maximum Contaminant Level established for drinking water by the U.S. Environmental Protection Agency. Triazine herbicide concentrations tended to be highest during late spring runoff after herbicide application. High concentrations of fecal indicator bacteria in surface water are a concern on the reservation with fecal coliform concentrations ranging from 4 to greater than 31,000 colonies per 100 milliliters of water with a median concentration of 570 colonies per 100 milliliters. More than one-half of the surface-water-quality samples exceeded the Kansas Department of Health and Environment contact recreation criteria of 200 and 2,000 colonies per 100 milliliters of water and were collected mostly during the spring and summer. Two wells had sodium concentrations of about 10 times the U.S. Environmental Protection Agengy health advisory level (HAL) of 20 mg/L; concentrations ranged from 241 to 336 mg/L. In water from two wells, sulfate concentrations exceeded 800 mg/L, more than three times the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level (SMCL) for drinking water of 250 mg/L. All but two of the eight ground-water-quality samples had dissolved-solids concentrations exceeding the SMCL of 500 mg/L. The highest concentration of 2,010 mg/L was more than four times the SMCL. Dissolved boron concentrations exceeded the U.S. Environmental Protection Agency 600-?g/L HAL in water from two of the seven wells sampled. Because the HAL is for a lifetime of exposure, the anticipated health risk due to dissolved boron is low. Dissolved iron concentrations in ground-water samples exceeded the 300-?g/L SMCL for treated drinking water in three of the seven wells sampled. Dissolved manganese concentrations in water from the same three wells also exceeded the established SMCL of 50 ?g/L. Dissolved pesticides were not detected in any of the well samples; however, there were degradation products of the herbicides alachlor and metolachlor in several samples. Insecticides were not detected in any ground-water-quality samples. Low concentrations of E. coli and fecal coliform bacteria were detected in water from two wells, and E. coli was detected in water from one well. Much higher concentrations of E. coli, fecal coliform, and fecal strepto

Interaction of chiral herbicides with soil microorganisms, algae and vascular plants.

PubMed

Asad, Muhammad Asad Ullah; Lavoie, Michel; Song, Hao; Jin, Yujian; Fu, Zhengwei; Qian, Haifeng

2017-02-15

Chiral herbicides are often used in agriculture as racemic mixtures, although studies have shown that the fate and toxicity of herbicide enantiomers to target and non-target plants can be enantioselective and that herbicide toxicity can be mediated by only one enantiomer. If one enantiomer is active against the target plant, the use of enantiomer-rich herbicide mixtures instead of racemic herbicides could decrease the amount of herbicide applied to a crop and the cost of herbicide application, as well as unintended toxic herbicide effects in the environment. Such a change in the management of herbicide applications requires in-depth knowledge and a critical analysis of the fate and effects of herbicide enantiomers in the environment. This review article first synthesizes the current state of knowledge on soil and plant biodegradation of herbicide enantiomers. Second, we discuss our understanding of the biochemical toxicity mechanisms associated with both enantiomers in target and non-target plants gained from state-of-the-art genomic, proteomic and metabolomic tools. Third, we present the emerging view on the "side effects" of herbicides in the root microbiome and their repercussions on target or non-target plant metabolism. Although our review of the literature indicates that the toxicity of herbicide enantiomers is highly variable depending on plant species and herbicides, we found general trends in the enantioselective toxic effects of different herbicides in vascular plants and algae. The present study will be helpful for pesticide risk assessments as well as for the management of applying enriched-enantiomer herbicides. Copyright © 2016 Elsevier B.V. All rights reserved.

Metabolism of 4-Chloronitrobenzene by the Yeast Rhodosporidium sp

PubMed Central

Corbett, Michael D.; Corbett, Bernadette R.

1981-01-01

The yeast Rhodosporidium sp. metabolized 4-chloronitrobenzene by a reductive pathway to give 4-chloroacetanilide and 4-chloro-2-hydroxyacetanilide as the major final metabolites. The intermediate production of 4-chloronitrosobenzene, 4-chlorophenylhydroxylamine, and 4-chloroaniline was demonstrated by high-pressure liquid chromatography. Additional studies with selected metabolites established that the metabolite 4-chloro-2-hydroxyacetanilide was produced by an initial Bamberger rearrangement of the hydroxylamine metabolite, followed by acetylation. Direct C hydroxylation of the aromatic ring was not observed in this species. No hydroxamic acid production was detected, even though significant concentrations of the nitroso and hydroxylamine precursors to this functional group were observed. PMID:16345757

Herbicides and transformation products in surface waters of the Midwestern United States

USGS Publications Warehouse

Battaglin, W.A.; Thurman, E.M.; Kalkhoff, S.J.; Porter, S.D.

2003-01-01

Most herbicides applied to crops are adsorbed by plants or transformed (degraded) in the soil, but small fractions are lost from fields and either move to streams in overland runoff, near surface flow, or subsurface drains, or they infiltrate slowly to ground water. Herbicide transformation products (TPs) can be more or less mobile and more or less toxic in the environment than their source herbicides. To obtain information on the concentrations of selected herbicides and TPs in surface waters of the Midwestern United States, 151 water samples were collected from 71 streams and five reservoir outflows in 1998. These samples were analyzed for 13 herbicides and 10 herbicide TPs. Herbicide TPs were found to occur as frequently or more frequently than source herbicides and at concentrations that were often larger than their source herbicides. Most samples contained a mixture of more than 10 different herbicides or TPs. The ratios of TPs to herbicide concentrations can be used to determine the source of herbicides in streams. Results of a two-component mixing model suggest that on average 90 percent or more of the herbicide mass in Midwestern streams during early summer runoff events originates from the runoff and 10 percent or less comes from increased ground water discharge.

Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay.

PubMed

Ma, Rong; Skelton, Joshua J; Riechers, Dean E

2015-09-07

In order to isolate and accurately determine rates of herbicide metabolism in an obligate-outcrossing dicot weed, waterhemp (Amaranthus tuberculatus), we developed an excised leaf assay combined with a vegetative cloning strategy to normalize herbicide uptake and remove translocation as contributing factors in herbicide-resistant (R) and -sensitive (S) waterhemp populations. Biokinetic analyses of organic pesticides in plants typically include the determination of uptake, translocation (delivery to the target site), metabolic fate, and interactions with the target site. Herbicide metabolism is an important parameter to measure in herbicide-resistant weeds and herbicide-tolerant crops, and is typically accomplished with whole-plant tests using radiolabeled herbicides. However, one difficulty with interpreting biokinetic parameters derived from whole-plant methods is that translocation is often affected by rates of herbicide metabolism, since polar metabolites are usually not mobile within the plant following herbicide detoxification reactions. Advantages of the protocol described in this manuscript include reproducible, accurate, and rapid determination of herbicide degradation rates in R and S populations, a substantial decrease in the amount of radiolabeled herbicide consumed, a large reduction in radiolabeled plant materials requiring further handling and disposal, and the ability to perform radiolabeled herbicide experiments in the lab or growth chamber instead of a greenhouse. As herbicide resistance continues to develop and spread in dicot weed populations worldwide, the excised leaf assay method developed and described herein will provide an invaluable technique for investigating non-target site-based resistance due to enhanced rates of herbicide metabolism and detoxification.

Inheritance of evolved resistance to a novel herbicide (pyroxasulfone).

PubMed

Busi, Roberto; Gaines, Todd A; Vila-Aiub, Martin M; Powles, Stephen B

2014-03-01

Agricultural weeds have rapidly adapted to intensive herbicide selection and resistance to herbicides has evolved within ecological timescales. Yet, the genetic basis of broad-spectrum generalist herbicide resistance is largely unknown. This study aims to determine the genetic control of non-target-site herbicide resistance trait(s) that rapidly evolved under recurrent selection of the novel lipid biosynthesis inhibitor pyroxasulfone in Lolium rigidum. The phenotypic segregation of pyroxasulfone resistance in parental, F1 and back-cross (BC) families was assessed in plants exposed to a gradient of pyroxasulfone doses. The inheritance of resistance to chemically dissimilar herbicides (cross-resistance) was also evaluated. Evolved resistance to the novel selective agent (pyroxasulfone) is explained by Mendelian segregation of one semi-dominant allele incrementally herbicide-selected at higher frequency in the progeny. In BC families, cross-resistance is conferred by an incompletely dominant single major locus. This study confirms that herbicide resistance can rapidly evolve to any novel selective herbicide agents by continuous and repeated herbicide use. The results imply that the combination of herbicide options (rotation, mixtures or combinations) to exploit incomplete dominance can provide acceptable control of broad-spectrum generalist resistance-endowing monogenic traits. Herbicide diversity within a set of integrated management tactics can be one important component to reduce the herbicide selection intensity. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Metabolism-Based Herbicide Resistance and Cross-Resistance in Crop Weeds: A Threat to Herbicide Sustainability and Global Crop Production1

PubMed Central

Yu, Qin; Powles, Stephen

2014-01-01

Weedy plant species that have evolved resistance to herbicides due to enhanced metabolic capacity to detoxify herbicides (metabolic resistance) are a major issue. Metabolic herbicide resistance in weedy plant species first became evident in the 1980s in Australia (in Lolium rigidum) and the United Kingdom (in Alopecurus myosuroides) and is now increasingly recognized in several crop-weed species as a looming threat to herbicide sustainability and thus world crop production. Metabolic resistance often confers resistance to herbicides of different chemical groups and sites of action and can extend to new herbicide(s). Cytochrome P450 monooxygenase, glycosyl transferase, and glutathione S-transferase are often implicated in herbicide metabolic resistance. However, precise biochemical and molecular genetic elucidation of metabolic resistance had been stalled until recently. Complex cytochrome P450 superfamilies, high genetic diversity in metabolic resistant weedy plant species (especially cross-pollinated species), and the complexity of genetic control of metabolic resistance have all been barriers to advances in understanding metabolic herbicide resistance. However, next-generation sequencing technologies and transcriptome-wide gene expression profiling are now revealing the genes endowing metabolic herbicide resistance in plants. This Update presents an historical review to current understanding of metabolic herbicide resistance evolution in weedy plant species. PMID:25106819

Natural Compounds as Next-Generation Herbicides

PubMed Central

Dayan, Franck E.; Duke, Stephen O.

2014-01-01

Herbicides with new modes of action (MOAs) are badly needed due to the rapidly evolving resistance to commercial herbicides, but a new MOA has not been introduced in over 20 years. The greatest pest management challenge for organic agriculture is the lack of effective natural product herbicides. The structural diversity and evolved biological activity of natural phytotoxins offer opportunities for the development of both directly used natural compounds and synthetic herbicides with new target sites based on the structures of natural phytotoxins. Natural phytotoxins are also a source for the discovery of new herbicide target sites that can serve as the focus of traditional herbicide discovery efforts. There are many examples of strong natural phytotoxins with MOAs other than those used by commercial herbicides, which indicates that there are molecular targets of herbicides that can be added to the current repertoire of commercial herbicide MOAs. PMID:24784133

Natural compounds as next-generation herbicides.

PubMed

Dayan, Franck E; Duke, Stephen O

2014-11-01

Herbicides with new modes of action (MOAs) are badly needed due to the rapidly evolving resistance to commercial herbicides, but a new MOA has not been introduced in over 20 years. The greatest pest management challenge for organic agriculture is the lack of effective natural product herbicides. The structural diversity and evolved biological activity of natural phytotoxins offer opportunities for the development of both directly used natural compounds and synthetic herbicides with new target sites based on the structures of natural phytotoxins. Natural phytotoxins are also a source for the discovery of new herbicide target sites that can serve as the focus of traditional herbicide discovery efforts. There are many examples of strong natural phytotoxins with MOAs other than those used by commercial herbicides, which indicates that there are molecular targets of herbicides that can be added to the current repertoire of commercial herbicide MOAs. © 2014 American Society of Plant Biologists. All Rights Reserved.

Environmental Quality: Environmental Protection and Enhancement

DTIC Science & Technology

2002-01-17

have an adverse effect on human health . These regulations are federally enforceable. Primacy states may have more stringent requirements. Primary...includes TT requirements for filtered and unfiltered systems that are specifically designed to protect against the adverse health effects of exposure to...MTBE (20) Alachlor ESA (36) Lead- 210 (9) Nitrobenzene (21) 1,2-diphenylhydrazine (37) Polonium - 210 (10) Terbacil (22) Diazinon (11) Acetochlor (23

Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay

PubMed Central

Ma, Rong; Skelton, Joshua J.; Riechers, Dean E.

2015-01-01

In order to isolate and accurately determine rates of herbicide metabolism in an obligate-outcrossing dicot weed, waterhemp (Amaranthus tuberculatus), we developed an excised leaf assay combined with a vegetative cloning strategy to normalize herbicide uptake and remove translocation as contributing factors in herbicide-resistant (R) and –sensitive (S) waterhemp populations. Biokinetic analyses of organic pesticides in plants typically include the determination of uptake, translocation (delivery to the target site), metabolic fate, and interactions with the target site. Herbicide metabolism is an important parameter to measure in herbicide-resistant weeds and herbicide-tolerant crops, and is typically accomplished with whole-plant tests using radiolabeled herbicides. However, one difficulty with interpreting biokinetic parameters derived from whole-plant methods is that translocation is often affected by rates of herbicide metabolism, since polar metabolites are usually not mobile within the plant following herbicide detoxification reactions. Advantages of the protocol described in this manuscript include reproducible, accurate, and rapid determination of herbicide degradation rates in R and S populations, a substantial decrease in the amount of radiolabeled herbicide consumed, a large reduction in radiolabeled plant materials requiring further handling and disposal, and the ability to perform radiolabeled herbicide experiments in the lab or growth chamber instead of a greenhouse. As herbicide resistance continues to develop and spread in dicot weed populations worldwide, the excised leaf assay method developed and described herein will provide an invaluable technique for investigating non-target site-based resistance due to enhanced rates of herbicide metabolism and detoxification. PMID:26383604

Removal of alachlor, diuron and isoproturon in water in a falling film dielectric barrier discharge (DBD) reactor combined with adsorption on activated carbon textile: Reaction mechanisms and oxidation by-products.

PubMed

Vanraes, Patrick; Wardenier, Niels; Surmont, Pieter; Lynen, Frederic; Nikiforov, Anton; Van Hulle, Stijn W H; Leys, Christophe; Bogaerts, Annemie

2018-07-15

A falling film dielectric barrier discharge (DBD) plasma reactor combined with adsorption on activated carbon textile material was optimized to minimize the formation of hazardous oxidation by-products from the treatment of persistent pesticides (alachlor, diuron and isoproturon) in water. The formation of by-products and the reaction mechanism was investigated by HPLC-TOF-MS. The maximum concentration of each by-product was at least two orders of magnitude below the initial pesticide concentration, during the first 10 min of treatment. After 30 min of treatment, the individual by-product concentrations had decreased to values of at least three orders of magnitude below the initial pesticide concentration. The proposed oxidation pathways revealed five main oxidation steps: dechlorination, dealkylation, hydroxylation, addition of a double-bonded oxygen and nitrification. The latter is one of the main oxidation mechanisms of diuron and isoproturon for air plasma treatment. To our knowledge, this is the first time that the formation of nitrificated intermediates is reported for the plasma treatment of non-phenolic compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

How benthic diatoms within natural communities respond to eight common herbicides with different modes of action.

PubMed

Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

2016-07-01

Herbicides are common pollutants of rivers in agricultural regions. These contaminants include various types of chemicals with different modes of toxic action. Herbicides can have toxic effects on freshwater benthic diatoms, the base of the aquatic food web. We examined the effects of (non-mixture) herbicide exposure to the health of diatoms for eight common herbicides with three different modes of action; the photosystem II (PSII) inhibitors: atrazine, simazine, hexazinone, tebuthiuron and diuron; two auxinic herbicides: MCPA and 2,4-D; and the EPSP synthase inhibitor: glyphosate. Benthic diatoms within riverine communities were exposed to each herbicide in rapid toxicity tests at concentrations of 50, 200 and 500μgL(-1). The most sensitive taxa were Gomphonema spp. and Encyonema gracilis. Navicula cryptotenella was the most tolerant to herbicide exposure. There was no significant effect of the different herbicide modes of action at the community level. Herbicide mode of action did not alter which taxa were most sensitive within the community and sensitivity rankings of the dominant diatom taxa were similar for each of the eight herbicides. The consistency of the results between herbicides suggests that freshwater benthic diatoms may be suitable in situ indicators for detecting the toxicity of herbicides with differing modes of action. Copyright © 2016 Elsevier B.V. All rights reserved.

Metabolism-based herbicide resistance and cross-resistance in crop weeds: a threat to herbicide sustainability and global crop production.

PubMed

Yu, Qin; Powles, Stephen

2014-11-01

Weedy plant species that have evolved resistance to herbicides due to enhanced metabolic capacity to detoxify herbicides (metabolic resistance) are a major issue. Metabolic herbicide resistance in weedy plant species first became evident in the 1980s in Australia (in Lolium rigidum) and the United Kingdom (in Alopecurus myosuroides) and is now increasingly recognized in several crop-weed species as a looming threat to herbicide sustainability and thus world crop production. Metabolic resistance often confers resistance to herbicides of different chemical groups and sites of action and can extend to new herbicide(s). Cytochrome P450 monooxygenase, glycosyl transferase, and glutathione S-transferase are often implicated in herbicide metabolic resistance. However, precise biochemical and molecular genetic elucidation of metabolic resistance had been stalled until recently. Complex cytochrome P450 superfamilies, high genetic diversity in metabolic resistant weedy plant species (especially cross-pollinated species), and the complexity of genetic control of metabolic resistance have all been barriers to advances in understanding metabolic herbicide resistance. However, next-generation sequencing technologies and transcriptome-wide gene expression profiling are now revealing the genes endowing metabolic herbicide resistance in plants. This Update presents an historical review to current understanding of metabolic herbicide resistance evolution in weedy plant species. © 2014 American Society of Plant Biologists. All Rights Reserved.

Spot Spraying Reduces Herbicide Concentrations in Runoff.

PubMed

Melland, Alice R; Silburn, D Mark; McHugh, Allen D; Fillols, Emilie; Rojas-Ponce, Samuel; Baillie, Craig; Lewis, Stephen

2016-05-25

Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots. Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites. Over 50% of all herbicides were transported in the dissolved phase of runoff, regardless of the herbicide's sediment-water partition coefficient. For most sites and herbicides, runoff herbicide concentrations decreased with decreasing spray coverage and with decreasing herbicide load in the soil and cane residues. Importantly, sites with higher infiltration prior to runoff and lower total runoff had lower runoff herbicide concentrations.

77 FR 10472 - Dow AgroScience LLC; Availability of Petition, Plant Pest Risk Assessment, and Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-22

... herbicides in the phenoxy auxin group (such as the herbicide 2,4-D) and resistance to grass herbicides in the... phenoxy auxin group (such as the herbicide 2,4-D) and resistance to grass herbicides in the...

Research methods in weed science: herbicide absorption and translocation in plants using radioisotopes

USDA-ARS?s Scientific Manuscript database

Herbicide absorption and translocation in plants is a key component in the study of herbicide physiology, mode of action, selectivity, resistance mechanisms, and in the registration process. Radioactive herbicides have been in use for over half-a-century in the research and study of herbicide absorp...

Bioactivity of Several Herbicides on the Nanogram Level Under Different Soil Moisture Conditions.

PubMed

Jung, S C; Kuk, Y I; Senseman, S A; Ahn, H G; Seong, C N; Lee, D J

2015-01-01

In this study, a double-tube centrifuge method was employed to determine the effects of soil moisture on the bioactivity of cafenstrole, pretilachlor, benfuresate, oxyfluorfen and simetryn. In general, the available herbicide concentration in soil solution (ACSS) showed little change as soil moisture increased for herbicides. The total available herbicide in soil solution (TASS) typically increased as soil moisture increased for all herbicides. The relationship between TASS and % growth rate based on dry weight showed strong linear relationships for both cafenstrole and pretilachlor, with r2 values of 0.95 and 0.84, respectively. Increasing TASS values were consistent with increasing herbicide water solubility, with the exception of the ionizable herbicide simetryn. Plant absorption and % growth rate exhibited a strong linear relationship with TASS. According to the results suggested that TASS was a better predictor of herbicidal bioactivity than ACSS for all herbicides under unsaturated soil moisture conditions.

Long-term trends in the intensity and relative toxicity of herbicide use

NASA Astrophysics Data System (ADS)

Kniss, Andrew R.

2017-04-01

Herbicide use is among the most criticized aspects of modern farming, especially as it relates to genetically engineered (GE) crops. Many previous analyses have used flawed metrics to evaluate herbicide intensity and toxicity trends. Here, I show that herbicide use intensity increased over the last 25 years in maize, cotton, rice and wheat. Although GE crops have been previously implicated in increasing herbicide use, herbicide increases were more rapid in non-GE crops. Even as herbicide use increased, chronic toxicity associated with herbicide use decreased in two out of six crops, while acute toxicity decreased in four out of six crops. In the final year for which data were available (2014 or 2015), glyphosate accounted for 26% of maize, 43% of soybean and 45% of cotton herbicide applications. However, due to relatively low chronic toxicity, glyphosate contributed only 0.1, 0.3 and 3.5% of the chronic toxicity hazard in those crops, respectively.

Why have no new herbicide modes of action appeared in recent years?

PubMed

Duke, Stephen O

2012-04-01

Herbicides with new modes of action are badly needed to manage the evolution of resistance of weeds to existing herbicides. Yet no major new mode of action has been introduced to the market place for about 20 years. There are probably several reasons for this. New potential products may have remained dormant owing to concerns that glyphosate-resistant (GR) crops have reduced the market for a new herbicide. The capture of a large fraction of the herbicide market by glyphosate with GR crops led to significantly diminished herbicide discovery efforts. Some of the reduced herbicide discovery research was also due to company consolidations and the availability of more generic herbicides. Another problem might be that the best herbicide molecular target sites may have already been discovered. However, target sites that are not utilized, for which there are inhibitors that are highly effective at killing plants, suggests that this is not true. Results of modern methods of target site discovery (e.g. gene knockout methods) are mostly not public, but there is no evidence of good herbicides with new target sites coming from these approaches. In summary, there are several reasons for a long dry period for new herbicide target sites; however, the relative magnitude of each is unclear. The economic stimulus to the herbicide industry caused by the evolution of herbicide-resistant weeds, especially GR weeds, may result in one or more new modes of action becoming available in the not too distant future. Copyright © 2011 Society of Chemical Industry.

Agricultural herbicide transport in a first-order intermittent stream, Nebraska, USA

USGS Publications Warehouse

Vogel, J.R.; Linard, J.I.

2011-01-01

The behavior of herbicides in surface waters is a function of many variables, including scale of the watershed, physical and chemical properties of the herbicide, physical and chemical properties of the soil, rainfall intensity, and time of year. In this study, the transport of 6 herbicides and 12 herbicide degradates was examined during the 2004 growing season in an intermediate-scale agricultural watershed (146 ha) that is drained by a first-order intermittent stream, and the mass load for each herbicide in the stream was estimated. The herbicide load during the first week of storm events after application ranged from 17% of annual load for trifluralin to 84% of annual load for acetochlor. The maximum weekly herbicide load in the stream was generally within the first 3 weeks after application for those compounds that were applied within the watershed during 2004, and later for herbicides not applied within the watershed during 2004 but still detected in the stream. The apparent dominant mode of herbicide transport in the stream-determined by analysis amongst herbicide and conservative ion concentrations at different points in the hydrograph and in base flow samples-was either overland runoff or shallow subsurface flow, depending on the elapsed time after application and type of herbicide. The load as a percentage of use (LAPU) for the parent compounds in this study was similar to literature values for those compounds applied by the farmer within the watershed, but smaller for those herbicides that had rainfall as their only source within the watershed.

HERBICIDE SENSITIVITY OF ECHINOCHLOA CRUS-GALLI POPULATIONS: A COMPARISON BETWEEN CROPPING SYSTEMS.

PubMed

Claerhout, S; De Cauwer, B; Reheul, D

2014-01-01

Echinochloa crus-galli populations exhibit high morphological variability and their response to herbicides varies from field to field. Differential response to herbicides could reflect differences in selection pressure, caused by years of cropping system related herbicide usage. This study investigates the relation between herbicide sensitivity of Echinochloa crus-galli populations and the cropping system to which they were subjected. The herbicide sensitivity of Echinochloa crus-galli was evaluated for populations collected on 18 fields, representing three cropping systems, namely (1) a long-term organic cropping system, (2) a conventional cropping system with corn in crop rotation or (3) a conventional cropping system with long-term monoculture of corn. Each cropping system was represented by 6 E. crus-galli populations. All fields were located on sandy soils. Dose-response pot experiments were conducted in the greenhouse to assess the effectiveness of three foliar-applied corn herbicides: nicosulfuron (ALS-inhibitor), cycloxydim (ACCase-inhibitor) and topramezone (HPPD-inhibitor), and two soil-applied corn herbicides: S-metolachlor and dimethenamid-P (both VLCFA-inhibitors). Foliar-applied herbicides were tested at a quarter, half and full recommended doses. Soil-applied herbicides were tested within a dose range of 0-22.5 g a.i. ha(-1) for S-metolachlor and 0-45 g a.i. ha(-1) for dimethenamid-P. Foliar-applied herbicides were applied at the three true leaves stage. Soil-applied herbicides were treated immediately after sowing the radicle-emerged seeds. All experiments were performed twice. The foliage dry weight per pot was determined four weeks after treatment. Plant responses to herbicides were expressed as biomass reduction (%, relative to the untreated control). Sensitivity to foliar-applied herbicides varied among cropping systems. Compared to populations from monoculture corn fields, populations originating from organic fields were significantly more sensitive to cycloxydim, topramezone and nicosulfuron (resp. 5.3%, 5.9% and 12.3%). Populations from the conventional crop rotation system showed intermediate sensitivity levels. Contrary to foliar-applied herbicides, the effectiveness of soil-applied herbicides was not affected by cropping system. Integrated weed management may be necessary to preserve herbicide efficacy on the long term.

Quantitative Evaluation of the Environmental Impact Quotient (EIQ) for Comparing Herbicides

PubMed Central

Kniss, Andrew R.; Coburn, Carl W.

2015-01-01

Various indicators of pesticide environmental risk have been proposed, and one of the most widely known and used is the environmental impact quotient (EIQ). The EIQ has been criticized by others in the past, but it continues to be used regularly in the weed science literature. The EIQ is typically considered an improvement over simply comparing the amount of herbicides applied by weight. Herbicides are treated differently compared to other pesticide groups when calculating the EIQ, and therefore, it is important to understand how different risk factors affect the EIQ for herbicides. The purpose of this work was to evaluate the suitability of the EIQ as an environmental indicator for herbicides. Simulation analysis was conducted to quantify relative sensitivity of the EIQ to changes in risk factors, and actual herbicide EIQ values were used to quantify the impact of herbicide application rate on the EIQ Field Use Rating. Herbicide use rate was highly correlated with the EIQ Field Use Rating (Spearman’s rho >0.96, P-value <0.001) for two herbicide datasets. Two important risk factors for herbicides, leaching and surface runoff potential, are included in the EIQ calculation but explain less than 1% of total variation in the EIQ. Plant surface half-life was the risk factor with the greatest relative influence on herbicide EIQ, explaining 26 to 28% of the total variation in EIQ for actual and simulated EIQ values, respectively. For herbicides, the plant surface half-life risk factor is assigned values without any supporting quantitative data, and can result in EIQ estimates that are contrary to quantitative risk estimates for some herbicides. In its current form, the EIQ is a poor measure of herbicide environmental impact. PMID:26121252

Quantitative Evaluation of the Environmental Impact Quotient (EIQ) for Comparing Herbicides.

PubMed

Kniss, Andrew R; Coburn, Carl W

2015-01-01

Various indicators of pesticide environmental risk have been proposed, and one of the most widely known and used is the environmental impact quotient (EIQ). The EIQ has been criticized by others in the past, but it continues to be used regularly in the weed science literature. The EIQ is typically considered an improvement over simply comparing the amount of herbicides applied by weight. Herbicides are treated differently compared to other pesticide groups when calculating the EIQ, and therefore, it is important to understand how different risk factors affect the EIQ for herbicides. The purpose of this work was to evaluate the suitability of the EIQ as an environmental indicator for herbicides. Simulation analysis was conducted to quantify relative sensitivity of the EIQ to changes in risk factors, and actual herbicide EIQ values were used to quantify the impact of herbicide application rate on the EIQ Field Use Rating. Herbicide use rate was highly correlated with the EIQ Field Use Rating (Spearman's rho >0.96, P-value <0.001) for two herbicide datasets. Two important risk factors for herbicides, leaching and surface runoff potential, are included in the EIQ calculation but explain less than 1% of total variation in the EIQ. Plant surface half-life was the risk factor with the greatest relative influence on herbicide EIQ, explaining 26 to 28% of the total variation in EIQ for actual and simulated EIQ values, respectively. For herbicides, the plant surface half-life risk factor is assigned values without any supporting quantitative data, and can result in EIQ estimates that are contrary to quantitative risk estimates for some herbicides. In its current form, the EIQ is a poor measure of herbicide environmental impact.

Glyphosate and dicamba herbicide tank mixture effects on native plant and non-genetically engineered soybean seedlings.

PubMed

Olszyk, David; Pfleeger, Thomas; Lee, E Henry; Plocher, Milton

2015-07-01

Crops engineered to contain genes for tolerance to multiple herbicides may be treated with several herbicides to manage weeds resistant to each herbicide. Thus, nearby non-target plants may be subjected to increased exposure to several herbicides used in combination. Of particular concern are native plants, as well as adjacent crops which have not been genetically engineered for tolerance to herbicides. We evaluated responses of seven species of native plants grown in a greenhouse and treated less than field application rates of glyphosate and/or dicamba: Andropogon gerardii, Asclepias syriaca, Eutrochium purpureum, Oenothera biennis, Polyganum lapathifolium, Solidago canadensis and Tridens flavus, and non-herbicide resistant soybean (Glycine max, Oregon line M4). Herbicide concentrations were 0.03 or 0.1 × field application rates of 1122 g ha(-1) active ingredient (a.i) (831 g ha(-1) acid glyphosate) for glyphosate and 562 g ha(-1) a.i. for dicamba. In general, plant growth responses to combinations of glyphosate and dicamba were less than the sum of growth responses to the individual herbicides (i.e., antagonistic effect), primarily when one or both herbicides alone caused a large reduction in growth. E. purpureum, P. lapathifolium and S. canadensis were the most sensitive species to both herbicides, while A. gerardii was the most tolerant, with no response to either herbicide. The combinations of herbicides resulted in responses most similar to that from dicamba alone for G. max and from glyphosate alone for T. flavus. The results of this study indicated the need for more data such as effects on native plants in the field to assess risks to non-target plants from combinations of herbicides.

Leaching and persistence of herbicides for kudzu (Pueraria montana) control on pine regeneration sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berisford, Yvette, C.; Bush, Parshall, B.; Taylor, John, W.

Kudzu is an exotic vine that threatens forests in the southeastern United States. It can climb, overtop, and subsequently kill new seedlings or mature trees. Herbicides are commonly used to control kudzu; however, eradication might require retreatment for 3 to 10 yr in young stands and 7 to 10 yr for mature stands. Clopyralid, picloram, triclopyr, metsulfuron, and tebuthiuron exert various degrees of control, depending on soil type, meteorological conditions, herbicide formulation, seasonal application, characteristics of the kudzu stand, and frequency and number of herbicide. Field residue data for soil or leachate are lacking for all of these herbicides whenmore » they are used in actual forest regeneration programs in the Coastal Plain. These data are needed to assess the relative potential for the herbicides to leach into groundwater or to move off-site into sensitive ecological areas of the Coastal Plain in which sandy soils predominate and the groundwater tends to be shallow. As part of an integrated pest management program to control kudzu on forest regeneration areas at the Savannah River Site near New Ellenton, SC, five herbicides were evaluated from the standpoints of herbicide leaching, kudzu control, and plant community development. Three herbicide chemical families were represented. This included pyridinecarboxylic acid herbicides (clopyralid, picloram 1 2,4-D, and triclopyr), a sulfonylurea herbicide (metsulfuron), and a substituted urea herbicide (tebuthiuron).« less

Herbicides and plant hormesis.

PubMed

Belz, Regina G; Duke, Stephen O

2014-05-01

Herbicide hormesis is commonly observed at subtoxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon are influenced by plant growth stage and physiological status, environmental factors, the endpoint measured and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugar cane 'ripeners' to enhance sucrose accumulation. The many factors that can influence the occurrence, the magnitude and the dose range of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g. in adjacent fields, when shielded by crop vegetation). Some weeds that have evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production. © 2014 Society of Chemical Industry.

Effects of herbicide-treated host plants on the development of Mamestra brassicae L. caterpillars.

PubMed

Hahn, Melanie; Geisthardt, Martin; Brühl, Carsten A

2014-11-01

Herbicides are widely used pesticides that affect plants by changing their chemistry. In doing so, herbicides might also influence the quality of plants as food for herbivores. To study the effects of herbicides on host plant quality, 3 plant species (Plantago lanceolata L., P. major L., and Ranunculus acris L.) were treated with sublethal rates of either a sulfonylurea (Atlantis WG, Bayer CropScience) or a glyphosate (Roundup LB Plus, Monsanto) herbicide, and the development of caterpillars of the cabbage moth Mamestra brassicae L. that fed on these plants was observed. Of the 6 tested plant-herbicide combinations, 1 combination (R. acris + sulfonylurea herbicide) resulted in significantly lower caterpillar weight, increased time to pupation, and increased overall development time compared with larvae that were fed unsprayed plants. These results might be caused by a lower nutritional value of these host plants or increased concentrations of secondary metabolites that are involved in plant defense. The results of the present and other studies suggest potential risks to herbivores that feed on host plants treated with sublethal rates of herbicides. However, as the effects of herbicides on host plant quality appear to be species-specific and as there are numerous plant-herbicide-herbivore relationships in agricultural landscapes, a general reduction in herbicide contamination of nontarget habitats (e.g., field margins) might mitigate the negative effects of herbicides on host plant quality. © 2014 SETAC.

Analysis of transcriptomic changes in Echinochloa colona in response to treatment with the herbicide imazamox

USDA-ARS?s Scientific Manuscript database

Herbicides are the most frequently used means of controlling weeds. For many herbicides the target site is known; however, it is considerably less clear how plant gene expression changes in response to herbicide exposure. Understanding which genes are activated in response to herbicides provides i...

Real World of Industrial Chemistry: The Challenge of Herbicides for Aquatic Weeds.

ERIC Educational Resources Information Center

Martin, Dean F.; Martin, Barbara B.

1985-01-01

Discusses problems in selecting the correct herbicide for use in controlling aquatic weeds, considering specificity, size of the market, fear of trace contaminants, and herbicide resistance in weeds. Also summarizes some successful herbicides, providing a table listing mode of action of some herbicides used for control of aquatic plants. (JN)

77 FR 41361 - Dow AgroSciences LLC; Availability of Petition for Determination of Nonregulated Status of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

... Genetically Engineered for Herbicide Tolerance AGENCY: Animal and Plant Health Inspection Service, USDA... broadleaf herbicides in the phenoxy auxin group (such as the herbicide 2,4-D) and the herbicides glyphosate...-44406-6, which has been genetically engineered for tolerance to broadleaf herbicides in the phenoxy...

A comparison of the herbicide tolerances of rare and common plants in an agricultural landscape.

PubMed

Egan, J Franklin; Graham, Ian M; Mortensen, David A

2014-03-01

Declining plant biodiversity in agroecosystems has often been attributed to escalating use of chemical herbicides, but other changes in farming systems, including the clearing of seminatural habitat fragments, confound the influence of herbicides. The present study introduces a new approach to evaluate the impacts of herbicide pollution on plant communities at landscape or regional scales. If herbicides are in fact a key factor shaping agricultural plant diversity, one would expect to see the signal of past herbicide impacts in the current plant community composition of an intensively farmed region, with common, successful species more tolerant to widely used herbicides than rare or declining species. Data from an extensive field survey of plant diversity in Lancaster County, Pennsylvania, USA, were compared with herbicide bioassay experiments in a greenhouse to test the hypothesis that common species possess higher herbicide tolerances than rare species. Five congeneric pairs of rare and common species were treated with 3 commonly used herbicide modes of action in bioassay experiments, and few significant differences were found in the tolerances of rare species relative to common species. These preliminary results suggest that other factors beyond herbicide exposure may be more important in shaping the distribution and abundance of plant species diversity across an agricultural landscape. © 2014 SETAC.

A generalised individual-based algorithm for modelling the evolution of quantitative herbicide resistance in arable weed populations.

PubMed

Liu, Chun; Bridges, Melissa E; Kaundun, Shiv S; Glasgow, Les; Owen, Micheal Dk; Neve, Paul

2017-02-01

Simulation models are useful tools for predicting and comparing the risk of herbicide resistance in weed populations under different management strategies. Most existing models assume a monogenic mechanism governing herbicide resistance evolution. However, growing evidence suggests that herbicide resistance is often inherited in a polygenic or quantitative fashion. Therefore, we constructed a generalised modelling framework to simulate the evolution of quantitative herbicide resistance in summer annual weeds. Real-field management parameters based on Amaranthus tuberculatus (Moq.) Sauer (syn. rudis) control with glyphosate and mesotrione in Midwestern US maize-soybean agroecosystems demonstrated that the model can represent evolved herbicide resistance in realistic timescales. Sensitivity analyses showed that genetic and management parameters were impactful on the rate of quantitative herbicide resistance evolution, whilst biological parameters such as emergence and seed bank mortality were less important. The simulation model provides a robust and widely applicable framework for predicting the evolution of quantitative herbicide resistance in summer annual weed populations. The sensitivity analyses identified weed characteristics that would favour herbicide resistance evolution, including high annual fecundity, large resistance phenotypic variance and pre-existing herbicide resistance. Implications for herbicide resistance management and potential use of the model are discussed. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Herbicide resistance and biodiversity: agronomic and environmental aspects of genetically modified herbicide-resistant plants.

PubMed

Schütte, Gesine; Eckerstorfer, Michael; Rastelli, Valentina; Reichenbecher, Wolfram; Restrepo-Vassalli, Sara; Ruohonen-Lehto, Marja; Saucy, Anne-Gabrielle Wuest; Mertens, Martha

2017-01-01

Farmland biodiversity is an important characteristic when assessing sustainability of agricultural practices and is of major international concern. Scientific data indicate that agricultural intensification and pesticide use are among the main drivers of biodiversity loss. The analysed data and experiences do not support statements that herbicide-resistant crops provide consistently better yields than conventional crops or reduce herbicide amounts. They rather show that the adoption of herbicide-resistant crops impacts agronomy, agricultural practice, and weed management and contributes to biodiversity loss in several ways: (i) many studies show that glyphosate-based herbicides, which were commonly regarded as less harmful, are toxic to a range of aquatic organisms and adversely affect the soil and intestinal microflora and plant disease resistance; the increased use of 2,4-D or dicamba, linked to new herbicide-resistant crops, causes special concerns. (ii) The adoption of herbicide-resistant crops has reduced crop rotation and favoured weed management that is solely based on the use of herbicides. (iii) Continuous herbicide resistance cropping and the intensive use of glyphosate over the last 20 years have led to the appearance of at least 34 glyphosate-resistant weed species worldwide. Although recommended for many years, farmers did not counter resistance development in weeds by integrated weed management, but continued to rely on herbicides as sole measure. Despite occurrence of widespread resistance in weeds to other herbicides, industry rather develops transgenic crops with additional herbicide resistance genes. (iv) Agricultural management based on broad-spectrum herbicides as in herbicide-resistant crops further decreases diversity and abundance of wild plants and impacts arthropod fauna and other farmland animals. Taken together, adverse impacts of herbicide-resistant crops on biodiversity, when widely adopted, should be expected and are indeed very hard to avoid. For that reason, and in order to comply with international agreements to protect and enhance biodiversity, agriculture needs to focus on practices that are more environmentally friendly, including an overall reduction in pesticide use. (Pesticides are used for agricultural as well non-agricultural purposes. Most commonly they are used as plant protection products and regarded as a synonym for it and so also in this text.).

Silvicultural use of herbicides in Pacific Northwest forests.

Treesearch

H. Gratkowski

1975-01-01

After a brief description of silvicultural problems, the author tells how to prescribe herbicidal sprays for aerial, application in Pacific Northwest forests. The publication offers a detailed discussion of the five basic considerations: (1) selection of the best herbicide or herbicides, (2) amount of herbicide to be applied per acre, (3) carriers, (4) volume of spray...

Development of reproduction in Allegheny hardwood stands after herbicide-clearcuts and herbicide-shelterwood cuts

Treesearch

Stephen B. Horsley

1982-01-01

Dense ground covers of fern and grass interfere with the regeneration of Allegheny hardwoods. An herbicide containing N-phosphonomethyl glycine controls the fern and grass, but also kills advance reproduction of desirable tree species. Preliminary results of an experiment comparing regeneration 3 years after herbicide-clearcuts and herbicide-shelterwood seed cuts...

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of pesticides in water by C-18 solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring

USGS Publications Warehouse

Zaugg, Steven D.; Sandstrom, Mark W.; Smith, Steven G.; Fehlberg, Kevin M.

1995-01-01

A method for the isolation of 41 pesticides and pesticide metabolites in natural-water samples using C-18 solid-phase extraction and determination by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction columns containing octadecyl-bonded porous silica to extract the pesticides. The columns are dried using carbon dioxide or nitrogen gas, and adsorbed pesticides are removed from the columns by elution with 3.0 milliliters of hexane-isopropanol (3:1). Extracted pesticides are determined by capillary- column gas chromatography/mass spectrometry with selected-ion monitoring of three characteristic ions. The upper concentration limit is 4 micrograms per liter (g/L) for most pesticides, with the exception of widely used corn herbicides--atrazine, alachlor, cyanazine, and metolachlor--which have upper concentration limits of 20 g/L. Single- operator method detection limits in reagent-water samples range from 0.001 to 0.018 g/L. Average short-term single-operator precision in reagent- water samples is 7 percent at the 0.1- and 1.0-g/L levels and 8 percent at the 0.01-g/L level. Mean recoveries in reagent-water samples are 73 percent at the 0.1- and 1.0-g/L levels and 83 percent at the 0.01-g/L level. The estimated holding time for pesticides after extraction on the solid-phase extraction columns was 7 days. An optional on-site extraction procedure allows for samples to be collected and processed at remote sites where it is difficult to ship samples to the laboratory within the recommended pre-extraction holding time.

Geochemistry of shallow ground water in coastal plain environments in the southeastern United States: Implications for aquifer susceptibility

USGS Publications Warehouse

Tesoriero, A.J.; Spruill, T.B.; Eimers, J.L.

2004-01-01

Ground-water chemistry data from coastal plain environments have been examined to determine the geochemical conditions and processes that occur in these areas and assess their implications for aquifer susceptibility. Two distinct geochemical environments were studied to represent a range of conditions: an inner coastal plain setting having more well-drained soils and lower organic carbon (C) content and an outer coastal plain environment that has more poorly drained soils and high organic C content. Higher concentrations of most major ions and dissolved inorganic and organic C in the outer coastal plain setting indicate a greater degree of mineral dissolution and organic matter oxidation. Accordingly, outer coastal plain waters are more reducing than inner coastal plain waters. Low dissolved oxygen (O2) and nitrate (NO 3-) concentrations and high iron (Fe) concentrations indicate that ferric iron (Fe (III)) is an important electron acceptor in this setting, while dissolved O2 is the most common terminal electron acceptor in the inner coastal plain setting. The presence of a wide range of redox conditions in the shallow aquifer system examined here underscores the importance of providing a detailed geochemical characterization of ground water when assessing the intrinsic susceptibility of coastal plain settings. The greater prevalence of aerobic conditions in the inner coastal plain setting makes this region more susceptible to contamination by constituents that are more stable under these conditions and is consistent with the significantly (p<0.05) higher concentrations of NO3- found in this setting. Herbicides and their transformation products were frequently detected (36% of wells sampled), however concentrations were typically low (<0.1 ??g/L). Shallow water table depths often found in coastal plain settings may result in an increased risk of the detection of pesticides (e.g., alachlor) that degrade rapidly in the unsaturated zone.

Hybridization using cytoplasmic male sterility, cytoplasmic herbicide tolerance, and herbicide tolerance from nuclear genes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beversdorf, W.D.; Erickson, L.R.; Grant, I.

An improved process is described for producing a substantially homogeneous population of plants of a predetermined hybrid variety of crop which is capable of undergoing self-pollination and cross-pollination. The process comprises: growing in a first planting area a substantially random population of cytoplasmic male sterile plants which exhibit cytoplasmic herbicide tolerance to at least one Type A herbicide and exhibit tolerance to at least one Type B herbicide which is attributable solely to homozygous dominant nuclear genes and male fertile plants which are homozygous recessive maintainer plants for the cytoplasmic male sterile plants and which lack the cytoplasmic herbicide tolerancemore » to at least one Type A herbicide and exhibit tolerance to at least one Type B herbicide attributable solely to the homozygous dominant nuclear genes.« less

Management of herbicide resistance in wheat cropping systems: learning from the Australian experience.

PubMed

Walsh, Michael J; Powles, Stephen B

2014-09-01

Herbicide resistance continues to escalate in weed populations infesting global wheat (Triticum aestivum L.) crops, threatening grain production and thereby food supply. Conservation wheat production systems are reliant on the use of efficient herbicides providing low-cost, selective weed control in intensive cropping systems. The resistance-driven loss of herbicide resources combined with limited potential for new herbicide molecules means greater emphasis must be placed on preserving existing herbicides. For more than two decades, since the initial recognition of the dramatic consequences of herbicide resistance, the challenge of introducing additional weed control strategies into herbicide-based weed management programmes has been formidable. Throughout this period, herbicide resistance has expanded unabated across the world's wheat production regions. However, in Australia, where herbicide resources have become desperately depleted, the adoption of harvest weed seed control is evidence, at last, of a successful approach to sustainable weed management in wheat production systems. Growers routinely including strategies to target weed seeds during crop harvest, as part of herbicide-based weed management programmes, are now realising significant weed control and crop production benefits. When combined with an attitude of zero weed tolerance, there is evidence of a sustainable weed control future for wheat production systems. The hard-learned lessons of Australian growers can now be viewed by global wheat producers as an example of how to stop the continual loss of herbicide resources in productive cropping systems. © 2013 Society of Chemical Industry.

Herbicides in vineyards reduce grapevine root mycorrhization and alter soil microorganisms and the nutrient composition in grapevine roots, leaves, xylem sap and grape juice.

PubMed

Zaller, Johann G; Cantelmo, Clemens; Santos, Gabriel Dos; Muther, Sandrina; Gruber, Edith; Pallua, Paul; Mandl, Karin; Friedrich, Barbara; Hofstetter, Ingrid; Schmuckenschlager, Bernhard; Faber, Florian

2018-06-03

Herbicides are increasingly applied in vineyards worldwide. However, not much is known on potential side effects on soil organisms or on the nutrition of grapevines (Vitis vinifera). In an experimental vineyard in Austria, we examined the impacts of three within-row herbicide treatments (active ingredients: flazasulfuron, glufosinate, glyphosate) and mechanical weeding on grapevine root mycorrhization; soil microorganisms; earthworms; and nutrient concentration in grapevine roots, leaves, xylem sap and grape juice. The three herbicides reduced grapevine root mycorrhization on average by 53% compared to mechanical weeding. Soil microorganisms (total colony-forming units, CFU) were significantly affected by herbicides with highest CFUs under glufosinate and lowest under glyphosate. Earthworms (surface casting activity, density, biomass, reproduction) or litter decomposition in soil were unaffected by herbicides. Herbicides altered nutrient composition in grapevine roots, leaves, grape juice and xylem sap that was collected 11 months after herbicide application. Xylem sap under herbicide treatments also contained on average 70% more bacteria than under mechanical weeding; however, due to high variability, this was not statistically significant. We conclude that interdisciplinary approaches should receive more attention when assessing ecological effects of herbicides in vineyard ecosystems.

Integrated pest management and weed management in the United States and Canada.

PubMed

Owen, Micheal D K; Beckie, Hugh J; Leeson, Julia Y; Norsworthy, Jason K; Steckel, Larry E

2015-03-01

There is interest in more diverse weed management tactics because of evolved herbicide resistance in important weeds in many US and Canadian crop systems. While herbicide resistance in weeds is not new, the issue has become critical because of the adoption of simple, convenient and inexpensive crop systems based on genetically engineered glyphosate-tolerant crop cultivars. Importantly, genetic engineering has not been a factor in rice and wheat, two globally important food crops. There are many tactics that help to mitigate herbicide resistance in weeds and should be widely adopted. Evolved herbicide resistance in key weeds has influenced a limited number of growers to include a more diverse suite of tactics to supplement existing herbicidal tactics. Most growers still emphasize herbicides, often to the exclusion of alternative tactics. Application of integrated pest management for weeds is better characterized as integrated weed management, and more typically integrated herbicide management. However, adoption of diverse weed management tactics is limited. Modifying herbicide use will not solve herbicide resistance in weeds, and the relief provided by different herbicide use practices is generally short-lived at best. More diversity of tactics for weed management must be incorporated in crop systems. © 2014 Society of Chemical Industry.

Herbicides as Weed Control Agents: State of the Art: II. Recent Achievements[C

PubMed Central

Kraehmer, Hansjoerg; van Almsick, Andreas; Beffa, Roland; Dietrich, Hansjoerg; Eckes, Peter; Hacker, Erwin; Hain, Ruediger; Strek, Harry John; Stuebler, Hermann; Willms, Lothar

2014-01-01

In response to changing market dynamics, the discovery of new herbicides has declined significantly over the past few decades and has only seen a modest upsurge in recent years. Nevertheless, the few introductions have proven to be interesting and have brought useful innovation to the market. In addition, herbicide-tolerant or herbicide-resistant crop technologies have allowed the use of existing nonselective herbicides to be extended into crops. An increasing and now major challenge is being posed by the inexorable increase in biotypes of weeds that are resistant to herbicides. This problem is now at a level that threatens future agricultural productivity and needs to be better understood. If herbicides are to remain sustainable, then it is a must that we adopt diversity in crop rotation and herbicide use as well as increase the use of nonchemical measures to control weeds. Nevertheless, despite the difficulties posed by resistant weeds and increased regulatory hurdles, new screening tools promise to provide an upsurge of potential herbicide leads. Our industry urgently needs to supply agriculture with new, effective resistance-breaking herbicides along with strategies to sustain their utility. PMID:25104721

Broad resistance to acetohydroxyacid-synthase-inhibiting herbicides in feral radish (Raphanus sativus L.) populations from Argentina.

PubMed

Pandolfo, Claudio E; Presotto, Alejandro; Moreno, Florencia; Dossou, Ida; Migasso, Juan P; Sakima, Ernesto; Cantamutto, Miguel

2016-02-01

Soon after the commercial release of sunflower cultivars resistant to imidazolinone herbicides, several uncontrolled feral radish (Raphanus sativus L.) populations were found in south-eastern Buenos Aires, Argentina. These populations were studied in field, glasshouse and laboratory experiments aiming to characterise their resistance profile and to develop management tools. Three feral radish accessions were highly resistant to ten active ingredients of five families of acetohydroxyacid synthase (AHAS)-inhibiting herbicides. Sequence analysis of the AHAS gene detected a Trp574Leu mutation in all resistant accessions. One accession with an intermediate level of resistance was heterozygous for this mutation, probably owing to gene exchange with a susceptible subpopulation located in the field margin. Herbicide-resistant and herbicide-susceptible radish could be controlled in sunflower by alternative herbicides. This is the first report of feral radish with resistance to herbicides belonging to all the AHAS-inhibiting herbicide families, conferred by Trp574Leu mutation in the AHAS gene. An appropriate herbicide rotation with alternative herbicides such as fluorochloridone or aclonifen and an increase in the diversity of cropping systems are important for minimising the prevalence of these biotypes. © 2015 Society of Chemical Industry.

Influence of an experimental herbicide on soil nitrogen-fixing bacteria and other microorganisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, L.M. Jr.; Hedrick, H.G.

Influence of an experimental herbicide on two isolates of soil nitrogen-fixing bacteria Rhizobium japonicum 3I1b110 and Azotobacter vinelandii ATCC 12837, was determined using a bioresponse assay, thin-layer chromatographic analysis, and changes in viable cells on the herbicide as the sole source of organic carbon. Seven bacterial and nine fungus isolates were also found by a soil enrichment technique to show utilization of the herbicide. A. vinelandii showed stimulation of growth in the first 4 days of exposure on the herbicide at 1,000 ppM. The herbicide then became toxic or was metabolized into toxic by-products. R. japonicum showed utilization of themore » herbicide by changes in growth rate as influenced by the inoculum concentration, the thoroughness of inoculum washing, and the concentration of herbicide. Using TLC assay techniques, the herbicide was found to be depleted in laboratory experiments by R. japonicum following 10 days of growth, without detectable nonmetabolic by-products. These findings suggested that the addition of the experimental herbicide to soils planted with bean crops could possibly influence the metabolic activity of R. japonicum as a symbiotic nitrogen-fixing bacterium. 5 figures, 1 table.« less

Herbicides as weed control agents: state of the art: II. Recent achievements.

PubMed

Kraehmer, Hansjoerg; van Almsick, Andreas; Beffa, Roland; Dietrich, Hansjoerg; Eckes, Peter; Hacker, Erwin; Hain, Ruediger; Strek, Harry John; Stuebler, Hermann; Willms, Lothar

2014-11-01

In response to changing market dynamics, the discovery of new herbicides has declined significantly over the past few decades and has only seen a modest upsurge in recent years. Nevertheless, the few introductions have proven to be interesting and have brought useful innovation to the market. In addition, herbicide-tolerant or herbicide-resistant crop technologies have allowed the use of existing nonselective herbicides to be extended into crops. An increasing and now major challenge is being posed by the inexorable increase in biotypes of weeds that are resistant to herbicides. This problem is now at a level that threatens future agricultural productivity and needs to be better understood. If herbicides are to remain sustainable, then it is a must that we adopt diversity in crop rotation and herbicide use as well as increase the use of nonchemical measures to control weeds. Nevertheless, despite the difficulties posed by resistant weeds and increased regulatory hurdles, new screening tools promise to provide an upsurge of potential herbicide leads. Our industry urgently needs to supply agriculture with new, effective resistance-breaking herbicides along with strategies to sustain their utility. © 2014 American Society of Plant Biologists. All Rights Reserved.

Delayed degradation in soil of foliar herbicides glyphosate and sulcotrione previously absorbed by plants: consequences on herbicide fate and risk assessment.

PubMed

Doublet, Jérémy; Mamy, Laure; Barriuso, Enrique

2009-10-01

Following application, pesticides can be intercepted and absorbed by weeds and/or crops. Plants containing pesticides residues may then reach the soil during the crop cycle or after harvest. However, the fate in soil of pesticides residues in plants is unknown. Two commonly used foliar herbicides, glyphosate and sulcotrione, (14)C-labeled, were applied on leaves of oilseed rape and/or maize, translocation was studied, and then soil incubations of aerial parts of plants containing herbicides residues were performed. Soil treated directly with herbicides was used as control. The effects of adjuvants on herbicide plant-absorption and subsequent soil-degradation were also investigated comparing herbicides application as active ingredients and as commercial formulations. The fate in soil of herbicides residues in plants was different from that of control, and different for glyphosate and sulcotrione. Mineralization in soil of glyphosate in crops decreased compared to control, and amounts of (14)C-extractable residues, mainly composed by the metabolite aminomethylphosphonic acid (AMPA), and non-extractable residues (NER) increased. In contrast, mineralization in soil of sulcotrione in maize increased compared to control, with a decrease in the (14)C-extractable residues and an increase in NER. The fate of both herbicides was influenced by the type of plant organ in which herbicide was incorporated, because of differences in herbicides bioavailability and organs biodegradability, but not by adjuvants. Absorption of both herbicides in plant delays their subsequent soil-degradation, and particularly, glyphosate persistence in soil could increase from two to six times. The modifications of herbicide degradation in soil due to interception by plants should be considered for environmental risks assessment.

Phytotoxicity of Four Photosystem II Herbicides to Tropical Seagrasses

PubMed Central

Flores, Florita; Collier, Catherine J.; Mercurio, Philip; Negri, Andrew P.

2013-01-01

Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zostera muelleri and Halodule uninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m ′), indicating reduced photosynthesis and maximum effective yields (Fv/Fm) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline. PMID:24098726

SulE, a Sulfonylurea Herbicide De-Esterification Esterase from Hansschlegelia zhihuaiae S113

PubMed Central

Hang, Bao-Jian; Hong, Qing; Xie, Xiang-Ting; Huang, Xing; Wang, Cheng-Hong; Li, Shun-Peng

2012-01-01

De-esterification is an important degradation or detoxification mechanism of sulfonylurea herbicide in microbes and plants. However, the biochemical and molecular mechanisms of sulfonylurea herbicide de-esterification are still unknown. In this study, a novel esterase gene, sulE, responsible for sulfonylurea herbicide de-esterification, was cloned from Hansschlegelia zhihuaiae S113. The gene contained an open reading frame of 1,194 bp, and a putative signal peptide at the N terminal was identified with a predicted cleavage site between Ala37 and Glu38, resulting in a 361-residue mature protein. SulE minus the signal peptide was synthesized in Escherichia coli BL21 and purified to homogeneity. SulE catalyzed the de-esterification of a variety of sulfonylurea herbicides that gave rise to the corresponding herbicidally inactive parent acid and exhibited the highest catalytic efficiency toward thifensulfuron-methyl. SulE was a dimer without the requirement of a cofactor. The activity of the enzyme was completely inhibited by Ag+, Cd2+, Zn2+, methamidophos, and sodium dodecyl sulfate. A sulE-disrupted mutant strain, ΔsulE, was constructed by insertion mutation. ΔsulE lost the de-esterification ability and was more sensitive to the herbicides than the wild type of strain S113, suggesting that sulE played a vital role in the sulfonylurea herbicide resistance of the strain. The transfer of sulE into Saccharomyces cerevisiae BY4741 conferred on it the ability to de-esterify sulfonylurea herbicides and increased its resistance to the herbicides. This study has provided an excellent candidate for the mechanistic study of sulfonylurea herbicide metabolism and detoxification through de-esterification, construction of sulfonylurea herbicide-resistant transgenic crops, and bioremediation of sulfonylurea herbicide-contaminated environments. PMID:22247165

Phytotoxicity of four photosystem II herbicides to tropical seagrasses.

PubMed

Flores, Florita; Collier, Catherine J; Mercurio, Philip; Negri, Andrew P

2013-01-01

Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zosteramuelleri and Haloduleuninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m '), indicating reduced photosynthesis and maximum effective yields (Fv/Fm ) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline.

NOVEL HERBICIDES

EPA Science Inventory

Low-dose, high-potency herbicides are defined as those herbicides with a maximum label application rate of 0.5 pounds of active ingredient per acre. Several classes of chemicals fall into this category, including the acetolactate synthase (ALSase) inhibitor herbicides, imidazoli...

Structural and functional effects of herbicides on non-target organisms in aquatic ecosystems with an emphasis on atrazine

USGS Publications Warehouse

Fairchild, James; Kortekamp, Andreas

2011-01-01

Herbicide use has increased dramatically around the world over the past 6 decades (Gianessi and Reigner, 2007). Few herbicides were in use in the 1950s. However, by 2001 approximately 1.14 billion kilograms of herbicides were applied globally for the control of undesireable vegetation in agricultural, silvicultural, lawncare, aquacultural, and irrigation/recreational water management activities (Kiely et al., 2004). Twenty-eight percent of the total mass of herbicides is applied in the United States, with the remaining 72 percent being applied elsewhere around the globe (Kiely et al., 2004). Herbicides represent 36% of global pesticide use, followed by insecticides (25%), fungicides (10%) and other chemical classes (Kiely et al., 2004). Agricultural production accounts for approximately 90% of herbicide use in the U.S. (Kiely et al., 2004). Gianessi and Reigner (2007) indicated that herbicides are routinely used on more than 90% of the area designated for large commercial crops including corn, soybeans, cotton, sugar beets, peanuts, and rice. Increased farm mechanization, technological advancements in production of inexpensive sources of inorganic nitrogen fertilizer (e.g., anhydrous ammonia), and conversion of forest, grassland, and wetland habitats to cropland has led to a tremendous increase in global food production over the past half-century. Herbicides have augmented advances in large-scale agricultural systems and have largely replaced mechanical and hand-weeding control mechanisms (Gianessi and Reigner, 2007). The wide-spread use of herbicides in agriculture has resulted in frequent chemical detections in surface and groundwaters (Gilliom, 2007). The majority of herbicides used are highly water soluble and are therefore prone to runoff from terrestrial environments. In additon, spray drift and atmospheric deposition can contribute to herbicide contamination of aquatic environments. Lastly, selected herbicides are deliberately applied to aquatic environments for controlling nuisance aquatic vegetation. Although aquatic herbicide exposure has been widely documented, these exposures are not necessarily related to adverse non-target ecological effects on natural communities in aquatic environments. This chapter evaluates the potential for effects of herbicides on the structure and function of aquatic envrionments at the population, community, and ecosystem levels of biological organization. In this manuscript I examine several critical aspects of the subject matter area: primary herbicides in use and chemical modes of action; the regulatory process used for registration and risk assessment of herbicides; data regarding non-target risks and the relative sensitivity of aquatic plants, inveretebrates, and fish to herbicides; and emerging areas of science regarding the potential for endocrine-disrupting effects of herbicides on aquatic vertebrates. Much of the focus of this paper is on atrazine due to the extensive database which exists regarding its fate and effects. 

Herbicide Persistence in Seawater Simulation Experiments

PubMed Central

Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P.

2015-01-01

Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes transporting a high proportion of the original herbicide from rivers into the GBR lagoon. PMID:26313296

Herbicide Persistence in Seawater Simulation Experiments.

PubMed

Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P

2015-01-01

Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes transporting a high proportion of the original herbicide from rivers into the GBR lagoon.

Structural and functional effects of herbicides on non-target organisms in aquatic ecosystems with an emphasis on atrazine

USGS Publications Warehouse

Fairchild, James; Kortekamp, Andreas

2011-01-01

Agricultural production accounts for approximately 90% of herbicide use in the U.S. (Kiely et al., 2004). Gianessi and Reigner (2007) indicated that herbicides are routinely used on more than 90% of the area designated for large commercial crops including corn, soybeans, cotton, sugar beets, peanuts, and rice. Increased farm mechanization, technological advancements in production of inexpensive sources of inorganic nitrogen fertilizer (e.g., anhydrous ammonia), and conversion of forest, grassland, and wetland habitats to cropland has led to a tremendous increase in global food production over the past half-century. Herbicides have augmented advances in large-scale agricultural systems and have largely replaced mechanical and hand-weeding control mechanisms (Gianessi and Reigner, 2007). The wide-spread use of herbicides in agriculture has resulted in frequent chemical detections in surface and groundwaters (Gilliom, 2007). The majority of herbicides used are highly water soluble and are therefore prone to runoff from terrestrial environments. In additon, spray drift and atmospheric deposition can contribute to herbicide contamination of aquatic environments. Lastly, selected herbicides are deliberately applied to aquatic environments for controlling nuisance aquatic vegetation. Although aquatic herbicide exposure has been widely documented, these exposures are not necessarily related to adverse non-target ecological effects on natural communities in aquatic environments. This chapter evaluates the potential for effects of herbicides on the structure and function of aquatic envrionments at the population, community, and ecosystem levels of biological organization. In this manuscript I examine several critical aspects of the subject matter area: primary herbicides in use and chemical modes of action; the regulatory process used for registration and risk assessment of herbicides; data regarding non-target risks and the relative sensitivity of aquatic plants, inveretebrates, and fish to herbicides; and emerging areas of science regarding the potential for endocrine-disrupting effects of herbicides on aquatic vertebrates. Much of the focus of this paper is on atrazine due to the extensive database which exists regarding its fate and effects.

DNA analysis of herbarium Specimens of the grass weed Alopecurus myosuroides reveals herbicide resistance pre-dated herbicides.

PubMed

Délye, Christophe; Deulvot, Chrystel; Chauvel, Bruno

2013-01-01

Acetyl-CoA carboxylase (ACCase) alleles carrying one point mutation that confers resistance to herbicides have been identified in arable grass weed populations where resistance has evolved under the selective pressure of herbicides. In an effort to determine whether herbicide resistance evolves from newly arisen mutations or from standing genetic variation in weed populations, we used herbarium specimens of the grass weed Alopecurus myosuroides to seek mutant ACCase alleles carrying an isoleucine-to-leucine substitution at codon 1781 that endows herbicide resistance. These specimens had been collected between 1788 and 1975, i.e., prior to the commercial release of herbicides inhibiting ACCase. Among the 734 specimens investigated, 685 yielded DNA suitable for PCR. Genotyping the ACCase locus using the derived Cleaved Amplified Polymorphic Sequence (dCAPS) technique identified one heterozygous mutant specimen that had been collected in 1888. Occurrence of a mutant codon encoding a leucine residue at codon 1781 at the heterozygous state was confirmed in this specimen by sequencing, clearly demonstrating that resistance to herbicides can pre-date herbicides in weeds. We conclude that point mutations endowing resistance to herbicides without having associated deleterious pleiotropic effects can be present in weed populations as part of their standing genetic variation, in frequencies higher than the mutation frequency, thereby facilitating their subsequent selection by herbicide applications.

Intelligent herbicide application system for reduced herbicide vegetation control : phase II-commercialization

DOT National Transportation Integrated Search

2008-12-01

This report describes the development of a commercial prototype intelligent herbicide application system : (IHAS). The improved design incorporates a parallel add-on type fluid handling system to allow existing : variable-rate herbicide injecti...

Fourier transform of delayed fluorescence as an indicator of herbicide concentration.

PubMed

Guo, Ya; Tan, Jinglu

2014-12-21

It is well known that delayed fluorescence (DF) from Photosystem II (PSII) of plant leaves can be potentially used to sense herbicide pollution and evaluate the effect of herbicides on plant leaves. The research of using DF as a measure of herbicides in the literature was mainly conducted in time domain and qualitative correlation was often obtained. Fourier transform is often used to analyze signals. Viewing DF signal in frequency domain through Fourier transform may allow separation of signal components and provide a quantitative method for sensing herbicides. However, there is a lack of an attempt to use Fourier transform of DF as an indicator of herbicide. In this work, the relationship between the Fourier transform of DF and herbicide concentration was theoretically modelled and analyzed, which immediately yielded a quantitative method to measure herbicide concentration in frequency domain. Experiments were performed to validate the developed method. Copyright © 2014 Elsevier Ltd. All rights reserved.

Whole Genome Sequence Analysis of an Alachlor and Endosulfan Degrading Micrococcus sp. strain 2385 Isolated from Ochlockonee River, Florida

PubMed Central

Pathak, Ashish; Chauhan, Ashvini; Ewida, Ayman Y.I.; Stothard, Paul

2016-01-01

We recently isolated Micrococcus sp. strain 2385 from Ochlockonee River, Florida and demonstrated potent biodegradative activity against two commonly used pesticides- alachlor [(2-chloro-2`,6`-diethylphenyl-N (methoxymethyl)acetanilide)] and endosulfan [(6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9methano-2,3,4-benzo(e)di-oxathiepin-3-oxide], respectively. To further identify the repertoire of metabolic functions possessed by strain 2385, a draft genome sequence was obtained, assembled, annotated and analyzed. The genome sequence of Micrococcus sp. strain 2385 consisted of 1,460,461,440 bases which assembled into 175 contigs with an N50 contig length of 50,109 bases and a coverage of 600x. The genome size of this strain was estimated at 2,431,226 base pairs with a G+C content of 72.8 and a total number of 2,268 putative genes. RAST annotated a total of 340 subsystems in the genome of strain 2385 along with the presence of 2,177 coding sequences. A genome wide survey indicated that that strain 2385 harbors a plethora of genes to degrade other pollutants including caprolactam, PAHs (such as naphthalene), styrene, toluene and several chloroaromatic compounds. PMID:27672405

Whole Genome Sequence Analysis of an Alachlor and Endosulfan Degrading Micrococcus sp. strain 2385 Isolated from Ochlockonee River, Florida.

PubMed

Pathak, Ashish; Chauhan, Ashvini; Ewida, Ayman Y I; Stothard, Paul

2016-01-01

We recently isolated Micrococcus sp. strain 2385 from Ochlockonee River, Florida and demonstrated potent biodegradative activity against two commonly used pesticides- alachlor [(2-chloro-2`,6`-diethylphenyl-N (methoxymethyl)acetanilide)] and endosulfan [(6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9methano-2,3,4-benzo(e)di-oxathiepin-3-oxide], respectively. To further identify the repertoire of metabolic functions possessed by strain 2385, a draft genome sequence was obtained, assembled, annotated and analyzed. The genome sequence of Micrococcus sp. strain 2385 consisted of 1,460,461,440 bases which assembled into 175 contigs with an N50 contig length of 50,109 bases and a coverage of 600x. The genome size of this strain was estimated at 2,431,226 base pairs with a G+C content of 72.8 and a total number of 2,268 putative genes. RAST annotated a total of 340 subsystems in the genome of strain 2385 along with the presence of 2,177 coding sequences. A genome wide survey indicated that that strain 2385 harbors a plethora of genes to degrade other pollutants including caprolactam, PAHs (such as naphthalene), styrene, toluene and several chloroaromatic compounds.

Delivery of calibration workshops covering herbicide application equipment : final report.

DOT National Transportation Integrated Search

2014-03-31

Proper herbicide sprayer set-up and calibration are critical to the success of the Oklahoma Department of Transportation (ODOT) herbicide program. Sprayer system set-up and calibration training is provided in annual continuing education herbicide wor...

Herbicide Resistant Weed Management

USDA-ARS?s Scientific Manuscript database

Metribuzin and rimsulfuron are the only two herbicides registered for postemergence broadleaf weed control in potatoes, and represent the two classes of herbicides, triazines and ALS inhibitors, with the most reported cases of resistant weeds world wide. Other postemergence grass herbicides belongin...

Herbicide residues in grapes and wine.

PubMed

Ying, G G; Williams, B

1999-05-01

The persistence of several common herbicides from grapes to wine has been studied. Shiraz, Tarrango and Doradillo grapes were separately sprayed with either norflurazon, oxyfluorfen, oxadiazon or trifluralin-persistent herbicides commonly used for weed control in vineyards. The dissipation of the herbicides from the grapes was followed for 28 days following treatment. Results showed that norflurazon was the most persist herbicide although there were detectable residues of all the herbicides on both red and white grapes at the end of the study period. The penetration of herbicides into the flesh of the grapes was found to be significantly greater for white grapes than for red grapes. Small-lot winemaking experiments showed that norflurazon persisted at levels close to the initial concentration through vinification and into the finished wine. The other herbicides degraded, essentially via first-order kinetics, within the period of "first fermentation" and had largely disappeared after 28 days. The use of charcoal together with filter pads, or with diatomaceous earth was shown to be very effective in removing herbicide residues from the wine. A 5% charcoal filter removed more than 96% of the norflurazon persisting in the treated wine.

Occurrence of selected herbicides and herbicide degradation products in Iowa's Ground Water, 1995

USGS Publications Warehouse

Kolpin, D.W.; Kalkhoff, S.J.; Goolsby, D.A.; Sneck-Fahrer, D. A.; Thurman, E.M.

1997-01-01

The occurrence of herbicide compounds had a significant, inverse relation to well depth and a significant, positive relation to dissolved-oxygen concentration. It is felt that both well depth and dissolved oxygen are acting as rough surrogates to ground-water age, with younger ground water being more likely to contain herbicide compounds. The occurrence of herbicide compounds was substantially different among the major aquifer types across Iowa, being detected in 82.5% of the alluvial, 81.8% of the bedrock/ karst region, 40.0% of the glacial-drift, and 25.0% of the bedrock/nonkarst region aquifers. The observed distribution was partially attributed to variations in general ground-water age among these aquifer types. A significant, inverse relation was determined between total herbicide compound concentrations in ground water and the average soil slope within a 2-km radius of sampled wells. Steeper soil slopes may increase the likelihood of surface runoff occurring rather than ground-water infiltration–decreasing the transport of herbicide compounds to ground water. As expected, a significant positive relation was determined between intensity of herbicide use and herbicide concentrations in ground water.

A herbicide structure-activity analysis of the antimalarial lead compound MMV007978 against Arabidopsis thaliana.

PubMed

Corral, Maxime G; Leroux, Julie; Tresch, Stefan; Newton, Trevor; Stubbs, Keith A; Mylne, Joshua S

2018-07-01

To fight herbicide-resistant weeds, new herbicides are needed; particularly ones with new modes of action. Building on the revelation that many antimalarial drugs are herbicidal, here we focus on the Medicines for Malaria Venture antimalarial lead compound MMV007978 that has herbicidal activity against the model plant Arabidopsis thaliana. Twenty-two variations of the lead compound thiophenyl motif revealed that change was tolerated provided ring size and charge were retained. MMV007978 was active against select monocot and dicot weeds, and physiological profiling indicated that its mode of action is related to germination and cell division. Of interest is the fact that the compound has a profile that is currently not found among known herbicides. We demonstrate that the antimalarial compound MMV007978 is also herbicidal and that exploiting lead compounds that are often understudied could lead to the identification of interesting herbicidal scaffolds. Further structural investigation of MMV007978 could provide improved herbicidal chemistries with a potential new mode of action. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Herbicides and nitrate in near-surface aquifers in the midcontinental United States, 1991

USGS Publications Warehouse

Kolpin, Dana W.; Burkart, Michael R.; Thurman, E. Michael

1994-01-01

Hydrogeologic factors, land use, agricultural practices, local features, and water chemistry were analyzed for possible relation to herbicide and excess-nitrate detections. Herbicides and excess nitrate were detected more frequently in near-surface unconsolidated aquifers than in nearsurface bedrock aquifers. The depth to the top of the aquifer was inversely related to the frequency of detection of herbicides and excess nitrate. The proximity of streams to sampled wells also affected the frequency of herbicide detection. Significant seasonal differences were determined for the frequency of herbicide detection, but not for the frequency of excess nitrate.

Acute and additive toxicity of ten photosystem-II herbicides to seagrass

NASA Astrophysics Data System (ADS)

Wilkinson, Adam D.; Collier, Catherine J.; Flores, Florita; Negri, Andrew P.

2015-11-01

Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (ΔF/Fm‧) by 50% at concentrations ranging from 3.5 μg l-1 (ametryn) to 132 μg l-1 (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ΔF/Fm‧.

Acute and additive toxicity of ten photosystem-II herbicides to seagrass

PubMed Central

Wilkinson, Adam D.; Collier, Catherine J.; Flores, Florita; Negri, Andrew P.

2015-01-01

Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/Fm′) by 50% at concentrations ranging from 3.5 μg l−1 (ametryn) to 132 μg l−1 (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/Fm′. PMID:26616444

Acute and additive toxicity of ten photosystem-II herbicides to seagrass.

PubMed

Wilkinson, Adam D; Collier, Catherine J; Flores, Florita; Negri, Andrew P

2015-11-30

Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/F(m)') by 50% at concentrations ranging from 3.5 μg l(-1) (ametryn) to 132 μg l(-1) (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/F(m)'.

The direct and indirect effects of a glyphosate-based herbicide and nutrients on Chironomidae (Diptera) emerging from small wetlands.

PubMed

Baker, Leanne F; Mudge, Joseph F; Houlahan, Jeff E; Thompson, Dean G; Kidd, Karen A

2014-09-01

Laboratory and mesocosm experiments have demonstrated that some glyphosate-based herbicides can have negative effects on benthic invertebrate species. Although these herbicides are among the most widely used in agriculture, there have been few multiple-stressor, natural system-based investigations of the impacts of glyphosate-based herbicides in combination with fertilizers on the emergence patterns of chironomids from wetlands. Using a replicated, split-wetland experiment, the authors examined the effects of 2 nominal concentrations (2.88 mg acid equivalents/L and 0.21 mg acid equivalents/L) of the glyphosate herbicide Roundup WeatherMax, alone or in combination with nutrient additions, on the emergence of Chironomidae (Diptera) before and after herbicide-induced damage to macrophytes. There were no direct effects of treatment on the structure of the Chironomidae community or on the overall emergence rates. However, after macrophyte cover declined as a result of herbicide application, there were statistically significant increases in emergence in all but the highest herbicide treatment, which had also received no nutrients. There was a negative relationship between chironomid abundance and macrophyte cover on the treated sides of wetlands. Fertilizer application did not appear to compound the effects of the herbicide treatments. Although direct toxicity of Roundup WeatherMax was not apparent, the authors observed longer-term impacts, suggesting that the indirect effects of this herbicide deserve more consideration when assessing the ecological risk of using herbicides in proximity to wetlands. © 2014 SETAC.

75 FR 4384 - Pesticide Products; Registration Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-27

... Park, NC 27709. Product name: Indaziflam 500 SC Herbicide. Active ingredient: Herbicide with Indaziflam.... Alexander Drive, Research Triangle Park, NC 27709. Product name: Indaziflam 200 SC Herbicide. Active ingredient: Herbicide with Indaziflam at 19.05%. Proposed use: Preemergent control of annual [[Page 4386...

Herbicide Trials in Intensively Cultured Populus Plantations in Northern Wisconsin

Treesearch

Daniel A. Netzer; Nonan V. Noste

1978-01-01

Populus had good survival and growth when planting sites had been treated with linuron, a pre-emergent herbicide, alone or in combination with paraquat, a post-emergent herbicide. the herbicide treatments that are most effective in intensive culture are discussed.

Degradation of Herbicides in the Tropical Marine Environment: Influence of Light and Sediment.

PubMed

Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; O'Brien, Jake; Flores, Florita; Negri, Andrew P

2016-01-01

Widespread contamination of nearshore marine systems, including the Great Barrier Reef (GBR) lagoon, with agricultural herbicides has long been recognised. The fate of these contaminants in the marine environment is poorly understood but the detection of photosystem II (PSII) herbicides in the GBR year-round suggests very slow degradation rates. Here, we evaluated the persistence of a range of commonly detected herbicides in marine water under field-relevant concentrations and conditions. Twelve-month degradation experiments were conducted in large open tanks, under different light scenarios and in the presence and absence of natural sediments. All PSII herbicides were persistent under control conditions (dark, no sediments) with half-lives of 300 d for atrazine, 499 d diuron, 1994 d hexazinone, 1766 d tebuthiuron, while the non-PSII herbicides were less persistent at 147 d for metolachlor and 59 d for 2,4-D. The degradation of herbicides was 2-10 fold more rapid in the presence of a diurnal light cycle and coastal sediments; apart from 2,4-D which degraded more slowly in the presence of light. Despite the more rapid degradation observed for most herbicides in the presence of light and sediments, the half-lives remained > 100 d for the PS II herbicides. The effects of light and sediments on herbicide persistence were likely due to their influence on microbial community composition and its ability to utilise the herbicides as a carbon source. These results help explain the year-round presence of PSII herbicides in marine systems, including the GBR, but more research on the transport, degradation and toxicity on a wider range of pesticides and their transformation products is needed to improve their regulation in sensitive environments.

Effects of glyphosate and two herbicide mixtures on microbial communities in prairie wetland ecosystems: a mesocosm approach.

PubMed

Sura, Srinivas; Waiser, Marley; Tumber, Vijay; Lawrence, John R; Cessna, Allan J; Glozier, Nancy

2012-01-01

A multitrophic outdoor mesocosm system was used to mimic a wetland ecosystem and to investigate the effects of glyphosate and two herbicide mixtures on wetland microbial communities. The glyphosate concentration used was 1000 times the environmentally relevant concentration (ERC). One herbicide mixture consisted of six auxin-type herbicides (2,4-D, MCPA, clopyralid, dicamba, dichlorprop, mecoprop), each at 1000 times the ERC. The second mixture was comprised of eight herbicides, including the six auxin-type herbicides as well as bromoxynil and glyphosate. For this mixture, a dose-response approach was used to treat mesocosms with the ERCs of each herbicide as the base concentration. Algal biomass and production and bacterial production and numbers for pelagic and attached communities were measured at different times over a 22-d period. The experimental results indicate that the eight-herbicide mixture, even at low concentrations, produced negative effects on microbial communities. Glyphosate on its own suppressed algal biomass and production for the duration of the study in pelagic and biofilm communities. Algal biomass and production, although initially depressed in the auxin-type herbicide treatment, were stimulated from Day 9 until experiment end. Due to their similar modes of action, the effects of this herbicide mixture appear to be a result of concentration addition. Such negative effects, however, were brief, and microbial communities recovered from herbicide exposure. Based on evidence presented in this study, it appears that glyphosate has a higher potential to inhibit primary production and chlorophyll content in pelagic and attached wetland algal communities than the auxin-type herbicide mixture. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Degradation of Herbicides in the Tropical Marine Environment: Influence of Light and Sediment

PubMed Central

Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; O'Brien, Jake; Flores, Florita; Negri, Andrew P.

2016-01-01

Widespread contamination of nearshore marine systems, including the Great Barrier Reef (GBR) lagoon, with agricultural herbicides has long been recognised. The fate of these contaminants in the marine environment is poorly understood but the detection of photosystem II (PSII) herbicides in the GBR year-round suggests very slow degradation rates. Here, we evaluated the persistence of a range of commonly detected herbicides in marine water under field-relevant concentrations and conditions. Twelve-month degradation experiments were conducted in large open tanks, under different light scenarios and in the presence and absence of natural sediments. All PSII herbicides were persistent under control conditions (dark, no sediments) with half-lives of 300 d for atrazine, 499 d diuron, 1994 d hexazinone, 1766 d tebuthiuron, while the non-PSII herbicides were less persistent at 147 d for metolachlor and 59 d for 2,4-D. The degradation of herbicides was 2–10 fold more rapid in the presence of a diurnal light cycle and coastal sediments; apart from 2,4-D which degraded more slowly in the presence of light. Despite the more rapid degradation observed for most herbicides in the presence of light and sediments, the half-lives remained > 100 d for the PS II herbicides. The effects of light and sediments on herbicide persistence were likely due to their influence on microbial community composition and its ability to utilise the herbicides as a carbon source. These results help explain the year-round presence of PSII herbicides in marine systems, including the GBR, but more research on the transport, degradation and toxicity on a wider range of pesticides and their transformation products is needed to improve their regulation in sensitive environments. PMID:27806103

Level of UV-B radiation influences the effects of glyphosate-based herbicide on the spotted salamander.

PubMed

Levis, Nicholas A; Johnson, Jarrett R

2015-07-01

Glyphosate-based herbicides are the number one pesticide in the United States and are used commonly around the world. Understanding the affects of glyphosate-based herbicides on non-target wildlife, for example amphibians, is critical for evaluation of regulations pertaining to the use of such herbicides. Additionally, it is important to understand how variation in biotic and abiotic environmental conditions, such as UV-B light regime, could potentially affect how glyphosate-based herbicides interact with non-target species. This study used artificial pond mesocosms to identify the effects of generic glyphosate-based herbicide (GLY-4 Plus) on mortality, cellular immune response, body size, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect moderate (UV(M)) and low (UV(L)) UV-B light regimes. Survival within a given UV-B level was unaffected by herbicide presence or absence. However, when herbicide was present, survival varied between UV-B levels with higher survival in UV(M) conditions. Herbicide presence in the UV(M) treatments also decreased body size and reduced cellular immune response. In the UV(L) treatments, the presence of herbicide increased body size and affected tail morphology. Finally, in the absence of herbicide, body size and cellular immune response were higher in UV(M) treatments compared to UV(L) treatments. Thus, the effects of herbicide on salamander fitness were dependent on UV-B level. As anthropogenic habitat modifications continue to alter landscapes that contain amphibian breeding ponds, salamanders may increasingly find themselves in locations with reduced canopy cover and increased levels of UV light. Our findings suggest that the probability of surviving exposure to the glyphosate-based herbicide used in this study may be elevated in more open canopy ponds, but the effects on other components of fitness may be varied and unexpected.

77 FR 30526 - Product Cancellation Order for Certain Pesticide Registrations

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-23

... Chemical name 000264-00438 Bronate Herbicide... MCPA,2-ethylhexyl ester. Bromoxynil octanoate. 000264-00477 Buctril + Atrazine Bromoxynil octanoate Herbicide. Atrazine. 000264-00586 Sedagri Batril 20W Bromoxynil Herbicide. octanoate. 000264-00650 Silverado Herbicide. Fenoxaprop-p-ethyl. 000264-00699 Rhino Brand MCPA,2...

Bioassay techniques for detecting root leakage of auxinic herbicides

USDA-ARS?s Scientific Manuscript database

Biological assay (bioassay) techniques are a simple way to determine the presence of herbicides in soil or other potting media. Understanding the fate of herbicides after absorption is important when guidelines for use are developed. Greenhouse studies were conducted with the herbicide aminocyclopyr...

Expanding the eco-evolutionary context of herbicide resistance research.

PubMed

Neve, Paul; Busi, Roberto; Renton, Michael; Vila-Aiub, Martin M

2014-09-01

The potential for human-driven evolution in economically and environmentally important organisms in medicine, agriculture and conservation management is now widely recognised. The evolution of herbicide resistance in weeds is a classic example of rapid adaptation in the face of human-mediated selection. Management strategies that aim to slow or prevent the evolution of herbicide resistance must be informed by an understanding of the ecological and evolutionary factors that drive selection in weed populations. Here, we argue for a greater focus on the ultimate causes of selection for resistance in herbicide resistance studies. The emerging fields of eco-evolutionary dynamics and applied evolutionary biology offer a means to achieve this goal and to consider herbicide resistance in a broader and sometimes novel context. Four relevant research questions are presented, which examine (i) the impact of herbicide dose on selection for resistance, (ii) plant fitness in herbicide resistance studies, (iii) the efficacy of herbicide rotations and mixtures and (iv) the impacts of gene flow on resistance evolution and spread. In all cases, fundamental ecology and evolution have the potential to offer new insights into herbicide resistance evolution and management. © 2014 Society of Chemical Industry.

Questions concerning the potential impact of glyphosate-based herbicides on amphibians.

PubMed

Wagner, Norman; Reichenbecher, Wolfram; Teichmann, Hanka; Tappeser, Beatrix; Lötters, Stefan

2013-08-01

Use of glyphosate-based herbicides is increasing worldwide. The authors review the available data related to potential impacts of these herbicides on amphibians and conduct a qualitative meta-analysis. Because little is known about environmental concentrations of glyphosate in amphibian habitats and virtually nothing is known about environmental concentrations of the substances added to the herbicide formulations that mainly contribute to adverse effects, glyphosate levels can only be seen as approximations for contamination with glyphosate-based herbicides. The impact on amphibians depends on the herbicide formulation, with different sensitivity of taxa and life stages. Effects on development of larvae apparently are the most sensitive endpoints to study. As with other contaminants, costressors mainly increase adverse effects. If and how glyphosate-based herbicides and other pesticides contribute to amphibian decline is not answerable yet due to missing data on how natural populations are affected. Amphibian risk assessment can only be conducted case-specifically, with consideration of the particular herbicide formulation. The authors recommend better monitoring of both amphibian populations and contamination of habitats with glyphosate-based herbicides, not just glyphosate, and suggest including amphibians in standardized test batteries to study at least dermal administration. Copyright © 2013 SETAC.

Phorate can reverse P450 metabolism-based herbicide resistance in Lolium rigidum.

PubMed

Busi, Roberto; Gaines, Todd Adam; Powles, Stephen

2017-02-01

Organophosphate insecticides can inhibit specific cytochrome P450 enzymes involved in metabolic herbicide resistance mechanisms, leading to synergistic interactions between the insecticide and the herbicide. In this study we report synergistic versus antagonistic interactions between the organophosphate insecticide phorate and five different herbicides observed in a population of multiple herbicide-resistant Lolium rigidum. Phorate synergised with three different herbicide modes of action, enhancing the activity of the ALS inhibitor chlorsulfuron (60% LD 50 reduction), the VLCFAE inhibitor pyroxasulfone (45% LD 50 reduction) and the mitosis inhibitor trifluralin (70% LD 50 reduction). Conversely, phorate antagonised the two thiocarbamate herbicides prosulfocarb and triallate with a 12-fold LD 50 increase. We report the selective reversal of P450-mediated metabolic multiple resistance to chlorsulfuron and trifluralin in the grass weed L. rigidum by synergistic interaction with the insecticide phorate, and discuss the putative mechanistic basis. This research should encourage diversity in herbicide use patterns for weed control as part of a long-term integrated management effort to reduce the risk of selection of metabolism-based multiple herbicide resistance in L. rigidum. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Herbicide-related signaling in plants reveals novel insights for herbicide use strategies, environmental risk assessment and global change assessment challenges.

PubMed

Alberto, Diana; Serra, Anne-Antonella; Sulmon, Cécile; Gouesbet, Gwenola; Couée, Ivan

2016-11-01

Herbicide impact is usually assessed as the result of a unilinear mode of action on a specific biochemical target with a typical dose-response dynamics. Recent developments in plant molecular signaling and crosstalk between nutritional, hormonal and environmental stress cues are however revealing a more complex picture of inclusive toxicity. Herbicides induce large-scale metabolic and gene-expression effects that go far beyond the expected consequences of unilinear herbicide-target-damage mechanisms. Moreover, groundbreaking studies have revealed that herbicide action and responses strongly interact with hormone signaling pathways, with numerous regulatory protein-kinases and -phosphatases, with metabolic and circadian clock regulators and with oxidative stress signaling pathways. These interactions are likely to result in mechanisms of adjustment that can determine the level of sensitivity or tolerance to a given herbicide or to a mixture of herbicides depending on the environmental and developmental status of the plant. Such regulations can be described as rheostatic and their importance is discussed in relation with herbicide use strategies, environmental risk assessment and global change assessment challenges. Copyright © 2016 Elsevier B.V. All rights reserved.

Herbicides do not ensure for higher wheat yield, but eliminate rare plant species

PubMed Central

Gaba, Sabrina; Gabriel, Edith; Chadœuf, Joël; Bonneu, Florent; Bretagnolle, Vincent

2016-01-01

Weed control is generally considered to be essential for crop production and herbicides have become the main method used for weed control in developed countries. However, concerns about harmful environmental consequences have led to strong pressure on farmers to reduce the use of herbicides. As food demand is forecast to increase by 50% over the next century, an in-depth quantitative analysis of crop yields, weeds and herbicides is required to balance economic and environmental issues. This study analysed the relationship between weeds, herbicides and winter wheat yields using data from 150 winter wheat fields in western France. A Bayesian hierarchical model was built to take account of farmers’ behaviour, including implicitly their perception of weeds and weed control practices, on the effectiveness of treatment. No relationship was detected between crop yields and herbicide use. Herbicides were found to be more effective at controlling rare plant species than abundant weed species. These results suggest that reducing the use of herbicides by up to 50% could maintain crop production, a result confirmed by previous studies, while encouraging weed biodiversity. Food security and biodiversity conservation may, therefore, be achieved simultaneously in intensive agriculture simply by reducing the use of herbicides. PMID:27453451

Limited fitness costs of herbicide-resistance traits in Amaranthus tuberculatus facilitate resistance evolution.

PubMed

Wu, Chenxi; Davis, Adam S; Tranel, Patrick J

2018-02-01

The fitness cost of herbicide resistance (HR) in the absence of herbicide selection plays a key role in HR evolution. Quantifying the fitness cost of resistance, however, is challenging, and there exists a knowledge gap in this area. A synthetic (artificially generated) Amaranthus tuberculatus population segregating for five types of HR was subjected to competitive growth conditions in the absence of herbicide selection for six generations. Fitness costs were quantified by using a combination of phenotyping and genotyping to monitor HR frequency changes over generations. In the absence of herbicide selection, a significant fitness cost was observed for resistance to acetolactate synthase-inhibiting herbicides, but not for resistances to atrazine (non-target-site resistance mechanism), protoporphyrinogen oxidase inhibitors, 4-hydroxyphenylpryuvate dioxygenase inhibitors or glyphosate. Glyphosate resistance was conferred by multiple mechanisms in the synthetic population, and further analysis revealed that one mechanism, amplification of the 5-enolypyruvylshikimate-3-phosphate synthase gene, did decrease in frequency. Our results indicate that herbicide-resistance mitigation strategies (e.g. herbicide rotation) that rely on the existence of fitness costs in the absence of herbicide selection likely will be largely ineffective in many cases. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

75 FR 17857 - Removal of Obsolete References to Herbicides Containing Dioxin

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-08

... Herbicides Containing Dioxin AGENCY: Department of Veterans Affairs. ACTION: Final rule. SUMMARY: The... health effects of exposure to herbicides containing dioxin and radiation to remove the obsolete references to herbicides containing dioxin. This final rule reflects changes made by the Agent Orange Act of...

Herbicide-Resistance in Crops and Weeds: A Historical and Current Perspective

USDA-ARS?s Scientific Manuscript database

Herbicides are the principal economic means of weed management on >90% of U.S. farmland. Herbicide-resistant crop cultivars have been used widely since 1995. Pest disciplines and other life sciences have various definitions of resistance that share commonalities. Development of herbicide resistant w...

Transcript markers of herbicide stress in Arabidopsis and their cross-species extrapolation to Brassica

EPA Science Inventory

Low concentrations and short environmental persistence times of some herbicides make it difficult to develop analytical methods to detect herbicide residues in plants or soils. In contrast, genomics may provide tools to identify herbicide exposure to plants in field settings. Usi...

Reducing Freshwater Toxicity while Maintaining Weed Control, Profits, And Productivity: Effects of Increased Crop Rotation Diversity and Reduced Herbicide Usage.

PubMed

Hunt, Natalie D; Hill, Jason D; Liebman, Matt

2017-02-07

Increasing crop rotation diversity while reducing herbicide applications may maintain effective weed control while reducing freshwater toxicity. To test this hypothesis, we applied the model USEtox 2.0 to data from a long-term Iowa field experiment that included three crop rotation systems: a 2-year corn-soybean sequence, a 3-year corn-soybean-oat/red clover sequence, and 4-year corn-soybean-oat/alfalfa-alfalfa sequence. Corn and soybean in each rotation were managed with conventional or low-herbicide regimes. Oat, red clover, and alfalfa were not treated with herbicides. Data from 2008-2015 showed that use of the low-herbicide regime reduced freshwater toxicity loads by 81-96%, and that use of the more diverse rotations reduced toxicity and system dependence on herbicides by 25-51%. Mean weed biomass in corn and soybean was <25 kg ha -1 in all rotation × herbicide combinations except the low-herbicide 3-year rotation, which contained ∼110 kg ha -1 of weed biomass. Corn and soybean yields and net returns were as high or higher for the 3- and 4-year rotations managed with the low-herbicide regime as for the conventional-herbicide 2-year rotation. These results indicate that certain forms of cropping system diversification and alternative weed management strategies can maintain yield, profit, and weed suppression while delivering enhanced environmental performance.

Response to low-dose herbicide selection in self-pollinated Avena fatua.

PubMed

Busi, Roberto; Girotto, Marcelo; Powles, Stephen B

2016-03-01

When applied at the correct plant stage and dose, herbicides are highly toxic to plants. At reduced, low herbicide doses (below the recommended dose) plants can survive and display continuous and quantitative variation in dose-survival responses. Recurrent (directional) selection studies can reveal whether such a phenotypic variation in plant survival response to low herbicide dose is heritable and leads to herbicide resistance. In a common experimental garden study, we have subjected a susceptible population of self-pollinated hexaploid Avena fatua to low-dose recurrent selection with the ACCase-inhibiting herbicide diclofop-methyl for three consecutive generations. Significant differences in response to low-dose diclofop-methyl selection were observed between the selected progenies and parent plants, with a twofold diclofop-methyl resistance and cross-resistance to ALS-inhibiting herbicides. Thus, the capacity of self-pollinated A. fatua to respond to low-dose herbicide selection is marginal, and it is much lower than in cross-pollinated L. rigidum. Lolium rigidum in the same experiment evolved 40-fold diclofop-methyl resistance by progressive enrichment of quantitative resistance-endowing traits. Cross-pollination rate, genetic variation and ploidy levels are identified as possible drivers affecting the contrasting capacity of Avena versus Lolium plants to respond to herbicide selection and the subsequent likelihood of resistance evolution at low herbicide dose usage. © 2015 Society of Chemical Industry.

Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact.

PubMed

Bonny, Sylvie

2016-01-01

Genetically modified (GM) crops have been and continue to be a subject of controversy despite their rapid adoption by farmers where approved. For the last two decades, an important matter of debate has been their impact on pesticide use, particularly for herbicide-tolerant (HT) crops. Some claim that these crops bring about a decrease in herbicide use, while others claim the opposite. In fact, since 1996, most cultivated GMOs have been GMHT crops, which involve the use of an associated herbicide, generally glyphosate. In their very first years of adoption, HT crops often led to some decrease in herbicide use. However, the repetition of glyphosate-tolerant crops and of glyphosate only applications in the same fields without sufficient alternation and herbicide diversity has contributed to the appearance of glyphosate-resistant weeds. These weeds have resulted in a rise in the use of glyphosate and other herbicides. This article explores this situation and the impacts of herbicide-resistant weeds, using an interdisciplinary approach and drawing on recent data. The paper analyzes the spread of GMHT crops worldwide and their consequences on herbicide use in the USA in particular. It then addresses the global development of glyphosate-resistant weeds and their impact, particularly focusing on the USA. Finally, the last section explores how industry, farmers, and weed scientists are coping with the spread of resistant weeds. The concluding comments deal more widely with trends in GM crops.

Genetically Modified Herbicide-Tolerant Crops, Weeds, and Herbicides: Overview and Impact

NASA Astrophysics Data System (ADS)

Bonny, Sylvie

2016-01-01

Genetically modified (GM) crops have been and continue to be a subject of controversy despite their rapid adoption by farmers where approved. For the last two decades, an important matter of debate has been their impact on pesticide use, particularly for herbicide-tolerant (HT) crops. Some claim that these crops bring about a decrease in herbicide use, while others claim the opposite. In fact, since 1996, most cultivated GMOs have been GMHT crops, which involve the use of an associated herbicide, generally glyphosate. In their very first years of adoption, HT crops often led to some decrease in herbicide use. However, the repetition of glyphosate-tolerant crops and of glyphosate only applications in the same fields without sufficient alternation and herbicide diversity has contributed to the appearance of glyphosate-resistant weeds. These weeds have resulted in a rise in the use of glyphosate and other herbicides. This article explores this situation and the impacts of herbicide-resistant weeds, using an interdisciplinary approach and drawing on recent data. The paper analyzes the spread of GMHT crops worldwide and their consequences on herbicide use in the USA in particular. It then addresses the global development of glyphosate-resistant weeds and their impact, particularly focusing on the USA. Finally, the last section explores how industry, farmers, and weed scientists are coping with the spread of resistant weeds. The concluding comments deal more widely with trends in GM crops.

Insight into the mode of action of 2,4-dichlorophenoxyacetic acid (2,4-D) as an herbicide.

PubMed

Song, Yaling

2014-02-01

2,4-Dichlorophenoxyacetic acid (2,4-D) was the first synthetic herbicide to be commercially developed and has commonly been used as a broadleaf herbicide for over 60 years. It is a selective herbicide that kills dicots without affecting monocots and mimics natural auxin at the molecular level. Physiological responses of dicots sensitive to auxinic herbicides include abnormal growth, senescence, and plant death. The identification of auxin receptors, auxin transport carriers, transcription factors response to auxin, and cross-talk among phytohormones have shed light on the molecular action mode of 2,4-D as a herbicide. Here, the molecular action mode of 2,4-D is highlighted according to the latest findings, emphasizing the physiological process, perception, and signal transduction under herbicide treatment. © 2013 Institute of Botany, Chinese Academy of Sciences.

Analysis of sugarcane herbicides in marine turtle nesting areas and assessment of risk using in vitro toxicity assays.

PubMed

Allan, Hannah L; van de Merwe, Jason P; Finlayson, Kimberly A; O'Brien, Jake W; Mueller, Jochen F; Leusch, Frederic D L

2017-10-01

Agricultural processes are associated with many different herbicides that can contaminate surrounding environments. In Queensland, Australia, herbicides applied to agricultural crops may pose a threat to valuable coastal habitats including nesting beaches for threatened loggerhead turtles (Caretta caretta). This study 1) measured concentrations of herbicides in the beach sand of Mon Repos, an important marine turtle nesting beach in Australia that is adjacent to significant sugarcane crops, and 2) investigated the toxicity of these herbicides to marine turtles using a cell-based assay. Samples of sand from turtle nest depth and water from surrounding agricultural drains and wetlands were collected during the wet season when herbicide runoff was expected to be the greatest and turtles were nesting. Samples were extracted using solid phase extraction and extracts were analysed using chemical analysis targeting herbicides, as well as bioanalytical techniques (IPAM-assay and loggerhead turtle skin cell cytotoxicity assay). Twenty herbicides were detected in areas between sugarcane crops and the nesting beach, seven of which were also detected in the sand extracts. Herbicides present in the nearby wetland were also detected in the beach sand, indicating potential contamination of the nesting beach via the river outlet as well as ground water. Although herbicides were detected in nesting sand, bioassays using loggerhead turtle skin cells indicated a low risk of acute toxicity at measured environmental concentrations. Further research should investigate potentially more subtle effects, such as endocrine disruption and mixture effects, to better assess the threat that herbicides pose to this population of marine turtles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE (registered trademark) and Scythe (registered trademark)

USDA-ARS?s Scientific Manuscript database

Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season- long weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of potential organic herbicides on weed control efficacy, crop injury, and y...

Potential organic herbicides for squash production: Pelargonic acid herbicides AXXE® and Scythe®

USDA-ARS?s Scientific Manuscript database

Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season-long weed control. Although corn gluten meal has shown promise as an early-season pre-emergent organic herbicide in squash production, any uncontrolled weeds can inflict serious yield reducti...

Discovery of new herbicide modes of action with natural phytotoxins

USDA-ARS?s Scientific Manuscript database

About 20 modes of action (MOAs) are utilized by commercial herbicides, and almost 30 years have passed since the last new MOA was introduced. Rapidly increasing evolution of resistance to herbicides with these MOAs has greatly increased the need for herbicides with new MOAs. Combinatorial chemistry ...

Vegetable Response to Herbicides Applied to Low-Density Polyethylene Mulch Prior to Transplant

USDA-ARS?s Scientific Manuscript database

Few herbicides are available for weed control in vegetables. The elimination of methyl bromide increases the need for herbicides. An experiment was conducted to evaluate crop injury from herbicides applied to LDPE mulch prior to transplant. Irrigation (1 cm) or no irrigation following crop transplan...

33 CFR 273.16 - Operations.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... (b) Safety in use of herbicides. Use of herbicides will be in accordance with the Occupational Safety and Health Act of 1970, reference § 273.12 (d) and (e). Some herbicides are toxic chemicals and must...; and eye protection. Some of the primary precautions which must be observed in handling herbicides are...

33 CFR 273.16 - Operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (b) Safety in use of herbicides. Use of herbicides will be in accordance with the Occupational Safety and Health Act of 1970, reference § 273.12 (d) and (e). Some herbicides are toxic chemicals and must...; and eye protection. Some of the primary precautions which must be observed in handling herbicides are...

33 CFR 273.16 - Operations.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (b) Safety in use of herbicides. Use of herbicides will be in accordance with the Occupational Safety and Health Act of 1970, reference § 273.12 (d) and (e). Some herbicides are toxic chemicals and must...; and eye protection. Some of the primary precautions which must be observed in handling herbicides are...

33 CFR 273.16 - Operations.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... (b) Safety in use of herbicides. Use of herbicides will be in accordance with the Occupational Safety and Health Act of 1970, reference § 273.12 (d) and (e). Some herbicides are toxic chemicals and must...; and eye protection. Some of the primary precautions which must be observed in handling herbicides are...

33 CFR 273.16 - Operations.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... (b) Safety in use of herbicides. Use of herbicides will be in accordance with the Occupational Safety and Health Act of 1970, reference § 273.12 (d) and (e). Some herbicides are toxic chemicals and must...; and eye protection. Some of the primary precautions which must be observed in handling herbicides are...

Tolerance evaluation of vegetatively established Miscanthus x giganteus to herbicides

USDA-ARS?s Scientific Manuscript database

In spite of the recent focus on herbicide resistant weeds, herbicide resistant weeds are not new to agriculture; the first herbicide resistant weed was documented in 1957, with the first widespread resistance occurring in common groundsel with atrazine in the early 1970’s. Glyphosate resistant weed...

Effectiveness of Glyphosate Mixed With Soil-Active Herbicides

Treesearch

James D. Haywood; Thomas W. Melder

1991-01-01

Broadcasting mixtures of glyphosate and soil-active herbicides over loblolly pine (Pinus taeda L.) seedlings may control established weeds and emerging weed seedlings better than either glyphosate or soil-active herbicides alone. However, herbicides will injure young pines if applied improperly. To examine seedling injury, we broadcast two rates of...

46 CFR Table 1 to Part 153 - Summary of Minimum Requirements

Code of Federal Regulations, 2011 CFR

2011-10-01

... Acetochlor A P II NR Open Open A .409 NA Acetone cyanohydrin A S/P II B/3 PV Closed A .238(a), .316, .336... Restr A .409, .525, .526, .1020 I-D Acrylamide solution (50% or less) D S II NR Open Closed NSR .409... .526 I-D Alachlor B S/P III NR Open Open A, C .238(a), .409, .440, .488, .908(a), (b) NA Alcohol (C6...

Herbicide Metabolites in Surface Water and Groundwater: Introduction and Overview

USGS Publications Warehouse

Thurman, E.M.; Meyer, M.T.

1996-01-01

Several future research topics for herbicide metabolites in surface and ground water are outlined in this chapter. They are herbicide usage, chemical analysis of metabolites, and fate and transport of metabolites in surface and ground water. These three ideas follow the themes in this book, which are the summary of a symposium of the American Chemical Society on herbicide metabolites in surface and ground water. First, geographic information systems allow the spatial distribution of herbicide-use data to be combined with geochemical information on fate and transport of herbicides. Next these two types of information are useful in predicting the kinds of metabolites present and their probable distribution in surface and ground water. Finally, methods development efforts may be focused on these specific target analytes. This chapter discusses these three concepts and provides an introduction to this book on the analysis, chemistry, and fate and transport of herbicide metabolites in surface and ground water.

The influence of reduced light intensity on the response of benthic diatoms to herbicide exposure.

PubMed

Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

2016-09-01

Herbicide pollution events in aquatic ecosystems often coincide with increased turbidity and reduced light intensity. It is therefore important to determine whether reduced light intensity can influence herbicide toxicity, especially to primary producers such as benthic diatoms. Benthic diatoms collected from 4 rivers were exposed to herbicides in 48 h rapid toxicity tests under high light (100 µmol m(-2)  s(-1) ) and low light (20 µmol m(-2)  s(-1) ) intensities. The effects of 2 herbicides (atrazine and glyphosate) were assessed on 26 freshwater benthic diatom taxa. There was no significant interaction of light and herbicide effects at the community level or on the majority (22 of 26) of benthic diatom taxa. This indicates that low light levels will likely have only a minor influence on the response of benthic diatoms to herbicides. Environ Toxicol Chem 2016;35:2252-2260. © 2016 SETAC. © 2016 SETAC.

Glyphosate herbicide affects belowground interactions between earthworms and symbiotic mycorrhizal fungi in a model ecosystem

PubMed Central

Zaller, Johann G.; Heigl, Florian; Ruess, Liliane; Grabmaier, Andrea

2014-01-01

Herbicides containing glyphosate are widely used in agriculture and private gardens, however, surprisingly little is known on potential side effects on non-target soil organisms. In a greenhouse experiment with white clover we investigated, to what extent a globally-used glyphosate herbicide affects interactions between essential soil organisms such as earthworms and arbuscular mycorrhizal fungi (AMF). We found that herbicides significantly decreased root mycorrhization, soil AMF spore biomass, vesicles and propagules. Herbicide application and earthworms increased soil hyphal biomass and tended to reduce soil water infiltration after a simulated heavy rainfall. Herbicide application in interaction with AMF led to slightly heavier but less active earthworms. Leaching of glyphosate after a simulated rainfall was substantial and altered by earthworms and AMF. These sizeable changes provide impetus for more general attention to side-effects of glyphosate-based herbicides on key soil organisms and their associated ecosystem services. PMID:25005713

Three-parameter modeling of the soil sorption of acetanilide and triazine herbicide derivatives.

PubMed

Freitas, Mirlaine R; Matias, Stella V B G; Macedo, Renato L G; Freitas, Matheus P; Venturin, Nelson

2014-02-01

Herbicides have widely variable toxicity and many of them are persistent soil contaminants. Acetanilide and triazine family of herbicides have widespread use, but increasing interest for the development of new herbicides has been rising to increase their effectiveness and to diminish environmental hazard. The environmental risk of new herbicides can be accessed by estimating their soil sorption (logKoc), which is usually correlated to the octanol/water partition coefficient (logKow). However, earlier findings have shown that this correlation is not valid for some acetanilide and triazine herbicides. Thus, easily accessible quantitative structure-property relationship models are required to predict logKoc of analogues of the these compounds. Octanol/water partition coefficient, molecular weight and volume were calculated and then regressed against logKoc for two series of acetanilide and triazine herbicides using multiple linear regression, resulting in predictive and validated models.

Using a Hydrological Model to Determine Environmentally Safer Windows for Herbicide Application

Treesearch

J.L. Michael; M.C. Smith; W.G. Knisel; D.G. Neary; W.P. Fowler; D.J. Turton

1996-01-01

A modification of the GLEAMS model was used to determine application windows which would optimise efficacy and environmental safety for herbicide application to a forest site. Herbicide/soil partition coefficients were determined using soil samples collected from the study site for two herbicides (imazapyr, Koc=46, triclopyr ester, K

77 FR 41367 - Dow AgroSciences LLC; Availability of Petition, Plant Pest Risk Assessment, and Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

... Assessment for Determination of Nonregulated Status of Soybean Genetically Engineered for Herbicide Tolerance... been genetically engineered for tolerance to broadleaf herbicides in the phenoxy auxin group (such as the herbicide 2,4-D) and the herbicide glufosinate. The petition has been submitted in accordance with...

40 CFR 174.533 - Glycine max Herbicide-Resistant Acetolactate Synthase (GM-HRA) inert ingredient; exemption from...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Glycine max Herbicide-Resistant... Glycine max Herbicide-Resistant Acetolactate Synthase (GM-HRA) inert ingredient; exemption from the requirement of a tolerance. Residues of Glycine max herbicide-resistant acetolactate synthase (GM-HRA) enzyme...

76 FR 70954 - Idaho Panhandle National Forests, Idaho; Idaho Panhandle National Forest Noxious Weed Treatment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-16

... registered herbicides is one of the various treatment methods that are proposed. The overall project goal is... insects; and herbicides that target specific invasive plant species. The application of herbicides would... spraying would be the primary method of applying herbicide in order to target individual and groups of...

40 CFR 174.533 - Glycine max Herbicide-Resistant Acetolactate Synthase (GM-HRA) inert ingredient; exemption from...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Glycine max Herbicide-Resistant... Glycine max Herbicide-Resistant Acetolactate Synthase (GM-HRA) inert ingredient; exemption from the requirement of a tolerance. Residues of Glycine max herbicide-resistant acetolactate synthase (GM-HRA) enzyme...

78 FR 34637 - Dow AgroSciences LLC; Notice of Intent To Prepare an Environmental Impact Statement for...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... of Nonregulated Status of Herbicide Resistant Corn and Soybeans, and Notice of Virtual Public... determination of nonregulated status of three cultivars of herbicide resistant corn and soybeans produced by Dow... certain broadleaf herbicides in the auxin growth regulator group (particularly the herbicide 2,4-D). The...

Effects of herbicide usage on water quality of selected streams in Wyoming

USGS Publications Warehouse

Butler, David L.

1980-01-01

During 1977 and 1978 the Wyoming Department of Agriculture, in conjunction with county weed and pest control districts, conducted a noxious-weed-control program in Wyoming. The herbicides primarily used were picloram, 2,4-D, and dicamba. The U.S. Geological Survey, in cooperation with the Wyoming Department of Agriculture, sampled and analyzed water from selected streams for these herbicides plus silvex; 2,4,5-T; and 2,4-DP.This report contains data for samples collected during 1977 and 1978. The most commonly detected herbicides in water samples were 2,4-D with 41-percent nonzero values and picloram with 34.5-percent nonzero values. Herbicide occurrence in bottom-material samples was uncommon; dicamba was found with 9-percent nonzero values. The maximum herbicide concentration in water was 1.1 micrograms per liter of 2,4-D, and the maximum herbicide concentration in bottom material was 8.0 micrograms per kilogram of 2,4-D. Based on available toxicity data and water-quality criteria, these herbicide concentrations do not constitute dangerous or harmful concentrations to humans or to the environment.

Population dynamics of weeds in oil palm (Elaeis guineensis Jacq.) circle weeding area affected by herbicide application

NASA Astrophysics Data System (ADS)

Sidik, S.; Purba, E.; Yakub, E. N.

2018-02-01

Weed problems in oil palm field were mainly overcomed by herbicide application. The application certain herbicides may lead to rapid population dynamic of certain species due to their different response to herbicides. Some species may less susceptible to certain herbicide whereas other species more susceptible. The objective of this study was to determine the population dynamic of weed species in circle weeding of oil palm in Serdang Bedagai, North Sumatra. Six treatments using glyphosate singly and mixture compared with manual weeding were evaluated for weed control. The treatments were arranged in a randomized block design with four replicates. Each treatment consisted of four circle weedings. The results showed that glyphosate 720 g a.i/ha + indaziflam 50 g a.i/hareduced seedbank and regrowth of weeds. Up to 12 weeks after application glyphosate 720 g a.i/ha + indaziflam 50 g a.i/ha is 29.46% total weeds dry weight compared to manual weeding. The effect of herbicide application on changes on the weed composition and weed seedbank are affected by the characteristic of herbicides and weed response to herbicide application.

Effect of some herbicides on the toxicity of certain molluscacides against Biomphalaria alexandrina snails.

PubMed

el-Fiki, S A; Mohamed, A M

1978-01-01

Studies dealing with the effect of some herbicides on the molluscicidal action of certain molluscicides against B. alexandrina have been carried out. In the first part of the study the toxicity of 3 molluscicides (Copper sulphate, Niclosamide and Frescon) and 3 herbicides (Gramaxone, Preforan and Treflan) was tested individually. Results indicated that the molluscicides were more potent than the herbicides. In the second part, snails were exposed for 24 hr to one of the tested herbicides using LC0 or (Sub. lethal conc) then the toxicity of molluscicides was determined among the same snails. Data indicated that pre-exposure to herbicides caused a synergistic action with copper sulphate, while with Niclosamide and Frescon marked antagonistic effect was observed. In the third part molluscicides and herbicides were mixed in different ratios (1:2, 1:1 and 2:1) and the toxicity of the mixtures was tested. A synergistic effect was observed in the case of copper sulphate plus various herbicides especially with Treflan at 1:2 ratio. With Niclosamide and Frescon slight antagonistic effect was detected.

Integration of agronomic practices with herbicides for sustainable weed management in aerobic rice.

PubMed

Anwar, M P; Juraimi, A S; Mohamed, M T M; Uddin, M K; Samedani, B; Puteh, A; Man, Azmi

2013-01-01

Till now, herbicide seems to be a cost effective tool from an agronomic view point to control weeds. But long term efficacy and sustainability issues are the driving forces behind the reconsideration of herbicide dependent weed management strategy in rice. This demands reappearance of physical and cultural management options combined with judicious herbicide application in a more comprehensive and integrated way. Keeping those in mind, some agronomic tools along with different manual weeding and herbicides combinations were evaluated for their weed control efficacy in rice under aerobic soil conditions. Combination of competitive variety, higher seeding rate, and seed priming resulted in more competitive cropping system in favor of rice, which was reflected in lower weed pressure, higher weed control efficiency, and better yield. Most of the herbicides exhibited excellent weed control efficiency. Treatments comprising only herbicides required less cost involvement but produced higher net benefit. On the contrary, treatments comprising both herbicide and manual weeding required high cost involvement and thus produced lower net benefit. Therefore, adoption of competitive rice variety, higher seed rate, and seed priming along with spraying different early-postemergence herbicides in rotation at 10 days after seeding (DAS) followed by a manual weeding at 30 DAS may be recommended from sustainability view point.

Current state of herbicides in herbicide-resistant crops.

PubMed

Green, Jerry M

2014-09-01

Current herbicide and herbicide trait practices are changing in response to the rapid spread of glyphosate-resistant weeds. Growers urgently needed glyphosate when glyphosate-resistant crops became available because weeds were becoming widely resistant to most commonly used selective herbicides, making weed management too complex and time consuming for large farm operations. Glyphosate made weed management easy and efficient by controlling all emerged weeds at a wide range of application timings. However, the intensive use of glyphosate over wide areas and concomitant decline in the use of other herbicides led eventually to the widespread evolution of weeds resistant to glyphosate. Today, weeds that are resistant to glyphosate and other herbicide types are threatening current crop production practices. Unfortunately, all commercial herbicide modes of action are over 20 years old and have resistant weed problems. The severity of the problem has prompted the renewal of efforts to discover new weed management technologies. One technology will be a new generation of crops with resistance to glyphosate, glufosinate and other existing herbicide modes of action. Other technologies will include new chemical, biological, cultural and mechanical methods for weed management. From the onset of commercialization, growers must now preserve the utility of new technologies by integrating their use with other weed management technologies in diverse and sustainable systems. © 2014 Society of Chemical Industry.

The experimental evolution of herbicide resistance in Chlamydomonas reinhardtii results in a positive correlation between fitness in the presence and absence of herbicides.

PubMed

Vogwill, T; Lagator, M; Colegrave, N; Neve, P

2012-10-01

Pleiotropic fitness trade-offs will be key determinants of the evolutionary dynamics of selection for pesticide resistance. However, for herbicide resistance, empirical support for a fitness cost of resistance is mixed, and it is therefore also questionable what further ecological trade-offs can be assumed to apply to herbicide resistance. Here, we test the existence of trade-offs by experimentally evolving herbicide resistance in Chlamydomonas reinhardtii. Although fitness costs are detected for all herbicides, we find that, counterintuitively, the most resistant populations also have the lowest fitness costs as measured by growth rate in the ancestral environment. Furthermore, after controlling for differences in the evolutionary dynamics of resistance to different herbicides, we also detect significant positive correlations between resistance, fitness in the ancestral environment and cross-resistance to other herbicides. We attribute this to the highest levels of nontarget-site resistance being achieved by fixing mutations that more broadly affect cellular physiology, which results in both more cross-resistance and less overall antagonistic pleiotropy on maximum growth rate. Consequently, the lack of classical ecological trade-offs could present a major challenge for herbicide resistance management. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Integration of Agronomic Practices with Herbicides for Sustainable Weed Management in Aerobic Rice

PubMed Central

Anwar, M. P.; Juraimi, A. S.; Mohamed, M. T. M.; Uddin, M. K.; Samedani, B.; Puteh, A.; Man, Azmi

2013-01-01

Till now, herbicide seems to be a cost effective tool from an agronomic view point to control weeds. But long term efficacy and sustainability issues are the driving forces behind the reconsideration of herbicide dependent weed management strategy in rice. This demands reappearance of physical and cultural management options combined with judicious herbicide application in a more comprehensive and integrated way. Keeping those in mind, some agronomic tools along with different manual weeding and herbicides combinations were evaluated for their weed control efficacy in rice under aerobic soil conditions. Combination of competitive variety, higher seeding rate, and seed priming resulted in more competitive cropping system in favor of rice, which was reflected in lower weed pressure, higher weed control efficiency, and better yield. Most of the herbicides exhibited excellent weed control efficiency. Treatments comprising only herbicides required less cost involvement but produced higher net benefit. On the contrary, treatments comprising both herbicide and manual weeding required high cost involvement and thus produced lower net benefit. Therefore, adoption of competitive rice variety, higher seed rate, and seed priming along with spraying different early-postemergence herbicides in rotation at 10 days after seeding (DAS) followed by a manual weeding at 30 DAS may be recommended from sustainability view point. PMID:24223513

A Novel Rice Cytochrome P450 Gene, CYP72A31, Confers Tolerance to Acetolactate Synthase-Inhibiting Herbicides in Rice and Arabidopsis1[C][W][OPEN

PubMed Central

Saika, Hiroaki; Horita, Junko; Taguchi-Shiobara, Fumio; Nonaka, Satoko; Nishizawa-Yokoi, Ayako; Iwakami, Satoshi; Hori, Kiyosumi; Matsumoto, Takashi; Tanaka, Tsuyoshi; Itoh, Takeshi; Yano, Masahiro; Kaku, Koichiro; Shimizu, Tsutomu; Toki, Seiichi

2014-01-01

Target-site and non-target-site herbicide tolerance are caused by the prevention of herbicide binding to the target enzyme and the reduction to a nonlethal dose of herbicide reaching the target enzyme, respectively. There is little information on the molecular mechanisms involved in non-target-site herbicide tolerance, although it poses the greater threat in the evolution of herbicide-resistant weeds and could potentially be useful for the production of herbicide-tolerant crops because it is often involved in tolerance to multiherbicides. Bispyribac sodium (BS) is an herbicide that inhibits the activity of acetolactate synthase. Rice (Oryza sativa) of the indica variety show BS tolerance, while japonica rice varieties are BS sensitive. Map-based cloning and complementation tests revealed that a novel cytochrome P450 monooxygenase, CYP72A31, is involved in BS tolerance. Interestingly, BS tolerance was correlated with CYP72A31 messenger RNA levels in transgenic plants of rice and Arabidopsis (Arabidopsis thaliana). Moreover, Arabidopsis overexpressing CYP72A31 showed tolerance to bensulfuron-methyl (BSM), which belongs to a different class of acetolactate synthase-inhibiting herbicides, suggesting that CYP72A31 can metabolize BS and BSM to a compound with reduced phytotoxicity. On the other hand, we showed that the cytochrome P450 monooxygenase CYP81A6, which has been reported to confer BSM tolerance, is barely involved, if at all, in BS tolerance, suggesting that the CYP72A31 enzyme has different herbicide specificities compared with CYP81A6. Thus, the CYP72A31 gene is a potentially useful genetic resource in the fields of weed control, herbicide development, and molecular breeding in a broad range of crop species. PMID:24406793

Herbicide monitoring in soil, runoff waters and sediments in an olive orchard.

PubMed

Calderon, Maria Jesus; De Luna, Elena; Gomez, Jose Alfonso; Hermosin, M Carmen

2016-11-01

Occurrences of surface water contamination by herbicides in areas where olive orchards are established reveal a need to understand soil processes affecting herbicide fate at field scale for this popular Mediterranean crop. A monitoring study with two herbicides (terbuthylazine and oxyfluorfen) in the first 2cm of soil, runoff waters, and sediments, was carried out after under natural rainfall conditions following winter herbicide application. At the end of the 107day field experiment, no residues of the soil applied terbuthylazine were recovered, whereas 42% of the oxyfluorfen applied remained in the top soil. Very low levels of both herbicides were measured in runoff waters; however, concentrations were slightly higher for terbuthylazine (0.53% of applied) than for oxyfluorfen (0.03% of applied), relating to their respective water solubilities. Congruent with soil residue data, 38.15% of the applied oxyfluorfen was found in runoff-sediment, compared to only 0.46% for terbuthylazine. Accordingly, the herbicide soil distribution coefficients measured within runoff field tanks was much greater for oxyfluorfen (Kd=3098) than for terbuthylazine (Kd=1.57). The herbicide oxyfluorfen is co-transported with sediment in runoff, remaining trapped and/or adsorbed to soil particle aggregates, due in part to its low water solubility. In contrast, terbuthylazine soil dissipation may be associated more so with leaching processes, favored by its high water solubility, low sorption, and slow degradation. By comparing these two herbicides, our results reaffirm the importance of herbicide physico-chemical properties in dictating their behavior in soil and also suggest that herbicides with low solubility, as seen in the case oxyfluorfen, remain susceptible to offsite transport associated with sediments. Copyright © 2016 Elsevier B.V. All rights reserved.

Recurrent selection with reduced 2,4-D amine doses results in the rapid evolution of 2,4-D herbicide resistance in wild radish (Raphanus raphanistrum L.).

PubMed

Ashworth, Michael B; Walsh, Michael J; Flower, Ken C; Powles, Stephen B

2016-11-01

When used at effective doses, weed resistance to auxinic herbicides has been slow to evolve when compared with other modes of action. Here we report the evolutionary response of a herbicide-susceptible population of wild radish (Raphanus raphanistrum L.) and confirm that sublethal doses of 2,4-dichlorophenoxyacetic acid (2,4-D) amine can lead to the rapid evolution of 2,4-D resistance and cross-resistance to acetolactate synthase (ALS)-inhibiting herbicides. Following four generations of 2,4-D selection, the progeny of a herbicide-susceptible wild radish population evolved 2,4-D resistance, increasing the LD 50 from 16 to 138 g ha -1 . Along with 2,4-D resistance, cross-resistance to the ALS-inhibiting herbicides metosulam (4.0-fold) and chlorsulfuron (4.5-fold) was evident. Pretreatment of the 2,4-D-selected population with the cytochrome P450 inhibitor malathion restored chlorsulfuron to full efficacy, indicating that cross-resistance to chlorsulfuron was likely due to P450-catalysed enhanced rates of herbicide metabolism. This study is the first to confirm the rapid evolution of auxinic herbicide resistance through the use of low doses of 2,4-D and serves as a reminder that 2,4-D must always be used at highly effective doses. With the introduction of transgenic auxinic-herbicide-resistant crops in the Americas, there will be a marked increase in auxinic herbicide use and therefore the risk of resistance evolution. Auxinic herbicides should be used only at effective doses and with diversity if resistance is to remain a minimal issue. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Comparative analysis of miRNAs of two rapeseed genotypes in response to acetohydroxyacid synthase-inhibiting herbicides by high-throughput sequencing.

PubMed

Hu, Maolong; Pu, Huiming; Gao, Jianqin; Long, Weihua; Chen, Feng; Zhang, Wei; Zhou, Xiaoyin; Peng, Qi; Chen, Song; Zhang, Jiefu

2017-01-01

Acetohydroxyacid synthase (AHAS), also called acetolactate synthase, is a key enzyme involved in the first step of the biosynthesis of the branched-chain amino acids valine, isoleucine and leucine. Acetohydroxyacid synthase-inhibiting herbicides (AHAS herbicides) are five chemical families of herbicides that inhibit AHAS enzymes, including imidazolinones (IMI), sulfonylureas (SU), pyrimidinylthiobenzoates, triazolinones and triazolopyrimidines. Five AHAS genes have been identified in rapeseed, but little information is available regarding the role of miRNAs in response to AHAS herbicides. In this study, an AHAS herbicides tolerant genotype and a sensitive genotype were used for miRNA comparative analysis. A total of 20 small RNA libraries were obtained of these two genotypes at three time points (0h, 24 h and 48 h) after spraying SU and IMI herbicides with two replicates. We identified 940 conserved miRNAs and 1515 novel candidate miRNAs in Brassica napus using high-throughput sequencing methods combined with computing analysis. A total of 3284 genes were predicted to be targets of these miRNAs, and their functions were shown using GO, KOG and KEGG annotations. The differentiation expression results of miRNAs showed almost twice as many differentiated miRNAs were found in tolerant genotype M342 (309 miRNAs) after SU herbicide application than in sensitive genotype N131 (164 miRNAs). In additiond 177 and 296 miRNAs defined as differentiated in sensitive genotype and tolerant genotype in response to SU herbicides. The miR398 family was observed to be associated with AHAS herbicide tolerance because their expression increased in the tolerant genotype but decreased in the sensitive genotype. Moreover, 50 novel miRNAs from 39 precursors were predicted. There were 8 conserved miRNAs, 4 novel miRNAs and 3 target genes were validated by quantitative real-time PCR experiment. This study not only provides novel insights into the miRNA content of AHAS herbicides tolerant rapeseed in response to AHAS herbicides, but also demonstrates that miRNAs may be involved in AHAS herbicides tolerance.

Comparative analysis of miRNAs of two rapeseed genotypes in response to acetohydroxyacid synthase-inhibiting herbicides by high-throughput sequencing

PubMed Central

Hu, Maolong; Pu, Huiming; Gao, Jianqin; Long, Weihua; Chen, Feng; Zhang, Wei; Zhou, Xiaoyin; Peng, Qi; Chen, Song; Zhang, Jiefu

2017-01-01

Acetohydroxyacid synthase (AHAS), also called acetolactate synthase, is a key enzyme involved in the first step of the biosynthesis of the branched-chain amino acids valine, isoleucine and leucine. Acetohydroxyacid synthase-inhibiting herbicides (AHAS herbicides) are five chemical families of herbicides that inhibit AHAS enzymes, including imidazolinones (IMI), sulfonylureas (SU), pyrimidinylthiobenzoates, triazolinones and triazolopyrimidines. Five AHAS genes have been identified in rapeseed, but little information is available regarding the role of miRNAs in response to AHAS herbicides. In this study, an AHAS herbicides tolerant genotype and a sensitive genotype were used for miRNA comparative analysis. A total of 20 small RNA libraries were obtained of these two genotypes at three time points (0h, 24 h and 48 h) after spraying SU and IMI herbicides with two replicates. We identified 940 conserved miRNAs and 1515 novel candidate miRNAs in Brassica napus using high-throughput sequencing methods combined with computing analysis. A total of 3284 genes were predicted to be targets of these miRNAs, and their functions were shown using GO, KOG and KEGG annotations. The differentiation expression results of miRNAs showed almost twice as many differentiated miRNAs were found in tolerant genotype M342 (309 miRNAs) after SU herbicide application than in sensitive genotype N131 (164 miRNAs). In additiond 177 and 296 miRNAs defined as differentiated in sensitive genotype and tolerant genotype in response to SU herbicides. The miR398 family was observed to be associated with AHAS herbicide tolerance because their expression increased in the tolerant genotype but decreased in the sensitive genotype. Moreover, 50 novel miRNAs from 39 precursors were predicted. There were 8 conserved miRNAs, 4 novel miRNAs and 3 target genes were validated by quantitative real-time PCR experiment. This study not only provides novel insights into the miRNA content of AHAS herbicides tolerant rapeseed in response to AHAS herbicides, but also demonstrates that miRNAs may be involved in AHAS herbicides tolerance. PMID:28950015

Bias analysis applied to Agricultural Health Study publications to estimate non-random sources of uncertainty.

PubMed

Lash, Timothy L

2007-11-26

The associations of pesticide exposure with disease outcomes are estimated without the benefit of a randomized design. For this reason and others, these studies are susceptible to systematic errors. I analyzed studies of the associations between alachlor and glyphosate exposure and cancer incidence, both derived from the Agricultural Health Study cohort, to quantify the bias and uncertainty potentially attributable to systematic error. For each study, I identified the prominent result and important sources of systematic error that might affect it. I assigned probability distributions to the bias parameters that allow quantification of the bias, drew a value at random from each assigned distribution, and calculated the estimate of effect adjusted for the biases. By repeating the draw and adjustment process over multiple iterations, I generated a frequency distribution of adjusted results, from which I obtained a point estimate and simulation interval. These methods were applied without access to the primary record-level dataset. The conventional estimates of effect associating alachlor and glyphosate exposure with cancer incidence were likely biased away from the null and understated the uncertainty by quantifying only random error. For example, the conventional p-value for a test of trend in the alachlor study equaled 0.02, whereas fewer than 20% of the bias analysis iterations yielded a p-value of 0.02 or lower. Similarly, the conventional fully-adjusted result associating glyphosate exposure with multiple myleoma equaled 2.6 with 95% confidence interval of 0.7 to 9.4. The frequency distribution generated by the bias analysis yielded a median hazard ratio equal to 1.5 with 95% simulation interval of 0.4 to 8.9, which was 66% wider than the conventional interval. Bias analysis provides a more complete picture of true uncertainty than conventional frequentist statistical analysis accompanied by a qualitative description of study limitations. The latter approach is likely to lead to overconfidence regarding the potential for causal associations, whereas the former safeguards against such overinterpretations. Furthermore, such analyses, once programmed, allow rapid implementation of alternative assignments of probability distributions to the bias parameters, so elevate the plane of discussion regarding study bias from characterizing studies as "valid" or "invalid" to a critical and quantitative discussion of sources of uncertainty.

33 CFR Appendix E to Part 273 - Preventive Safety Measures in Handling of Herbicides

Code of Federal Regulations, 2012 CFR

2012-07-01

... Handling of Herbicides E Appendix E to Part 273 Navigation and Navigable Waters CORPS OF ENGINEERS...—Preventive Safety Measures in Handling of Herbicides 1. Follow the label on each container before using the... accidental poisoning to the public or domestic animals. 3. Smoking is not permitted while herbicides are...

75 FR 60807 - Notice of Availability of the Record of Decision for Vegetation Treatments Using Herbicides on...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-01

... Herbicides on Bureau of Land Management Lands in Oregon Final Environmental Impact Statement AGENCY: Bureau... prepared a Record of Decision (ROD) for Vegetation Treatments Using Herbicides on Bureau of Land Management... Treatments Using Herbicides on Bureau of Land Management Lands in Oregon, notice of which was published in...

33 CFR Appendix E to Part 273 - Preventive Safety Measures in Handling of Herbicides

Code of Federal Regulations, 2013 CFR

2013-07-01

... Handling of Herbicides E Appendix E to Part 273 Navigation and Navigable Waters CORPS OF ENGINEERS...—Preventive Safety Measures in Handling of Herbicides 1. Follow the label on each container before using the... accidental poisoning to the public or domestic animals. 3. Smoking is not permitted while herbicides are...

Herbicide options for hardwood management

Treesearch

Andrew W. Ezell; A. Brady Self

2016-01-01

The use of herbicides in hardwood management presents special problems in that many of the most effective herbicides are either designed to control hardwoods or the product is not labeled for such applications. Numerous studies involving herbicide application in hardwoods have been completed at Mississippi State University. This paper is a compilation of results from...

33 CFR Appendix E to Part 273 - Preventive Safety Measures in Handling of Herbicides

Code of Federal Regulations, 2014 CFR

2014-07-01

... Handling of Herbicides E Appendix E to Part 273 Navigation and Navigable Waters CORPS OF ENGINEERS...—Preventive Safety Measures in Handling of Herbicides 1. Follow the label on each container before using the... accidental poisoning to the public or domestic animals. 3. Smoking is not permitted while herbicides are...

Midstory hardwood species respond differently to chainsaw girdle method and herbicide treatment

Treesearch

Ronald A. Rathfon; Michael R. Saunders

2013-01-01

Foresters in the Central Hardwoods Region commonly fell or girdle interfering trees and apply herbicide to the cut surface when performing intermediate silvicultural treatments. The objective of this study was to compare the use of single and double chainsaw girdle methods in combination with a herbicide treatment and, within the double girdle method, compare herbicide...

Kudzu eradication trials testing fifteen herbicides

Treesearch

James H. Miller

1986-01-01

Two studies examined herbicide treatments for controlling kudzu [Pueraria lobata (Willd.) Ohwi]. In one study, fifteen herbicides were tested at 1 or 2 rates at 5 locations. Treatments and re-treatments occurred over a 2-yr period. The most effective herbicides were picloram pellets (4.7 and 5.8 lb ai/a), tebuthiuron pellets (6 lb ai/a), and picloram...

Soil microbial community response to surfactants and herbicides in two soils

USDA-ARS?s Scientific Manuscript database

The impact of herbicides on more than just the target weed and the effect of some herbicides on the soil biota is of environmental interest. The surfactants that are often used with herbicides are also coming under fire as a potential harm to the soil life. We used a silt loam and a silty clay loam ...

[Purification and structural identification of herbicides from Botrytis cinerea].

PubMed

Zheng, Meng; Xu, Kuo; Dong, Jingao

2008-10-01

Toxin produced by phytopathogenic fungi is one of the important microbial herbicides. We found a new compound with herbicidal activity. Five different ultraviolet absorption components were isolated from the filtrate of Botrytis cinerea isolate 7-3 culture. Of the five components, one showed strong inhibitory to Digitaria sanguinalis. The pure fraction with high herbicidal activity was obtained by HPLC purification. Its structure was identified as 10-syn-dihydrobotrydial by Ultraviolet and Visible Spectroscopy, Infrared Spectrum, Nuclear Magnetic Resonance Spectroscopy analysis. The findings are important for future preparation and application of the herbicide.

Raw or incubated olive-mill wastes and its biotransformed products as agricultural soil amendments-effect on sorption-desorption of triazine herbicides.

PubMed

Delgado-Moreno, Laura; Almendros, Gonzalo; Peña, Aránzazu

2007-02-07

Raw olive-mill waste and soil amendments obtained from their traditional composting or vermicomposting were added, at rates equivalent to 200 Mg ha-1, to a calcareous silty clay loam soil in a laboratory test, in order to improve its fertility and physicochemical characteristics. In particular, the effects on the sorption-desorption processes of four triazine herbicides have been examined. We found that comparatively hydrophobic herbicides terbuthylazine and prometryn increased their retention on amended soil whereas the more polar herbicides simazine and cyanazine were less affected. Soil application of olive cake, without transformation, resulted in the highest herbicide retention. Its relatively high content in aliphatic fractions and lipids could explain the increased herbicide retention through hydrophobic bonding and herbicide diffusion favored by poorly condensed macromolecular structures. On the other hand, the condensed aromatic structure of the compost and vermicompost from olive cake could hinder diffusion processes, resulting in lower herbicide sorption. In fact, the progressive humification in soil of olive-mill solid waste led to a decrease of sorption capacity, which suggested important changes in organic matter quality and interactions during the mineralization process. When soil amended with vermicompost was incubated for different periods of time, the enhanced herbicide sorption capacity persisted for 2 months. Pesticide desorption was reduced by the addition of fresh amendments but was enhanced during the transformation process of amendments in soil. Our results indicate the potential of soil amendments based on olive-mill wastes in the controlled, selective release of triazine herbicides, which varies depending on the maturity achieved by their biological transformation.

Pre-breeding of lentil (Lens culinaris Medik.) for herbicide resistance through seed mutagenesis

PubMed Central

Rizwan, Muhammad; Aslam, Muhammad; Asghar, Muhammad Jawad; Abbas, Ghulam; Shah, Tariq Mahmud; Shimelis, Hussein

2017-01-01

Lentil is a poor competitor of weeds and its sensitivity to herbicides is a major hurdle for large scale production. The present study was conducted to select herbicide resistant lentil genotypes through seed mutagenesis. Seeds of three advanced lentil genotypes (LPP 11001, LPP 11100 and LPP 11116) were treated with two different concentrations of ethyl methanesulfonate (EMS; 0.1 and 0.2%), hydrazine hydrate (HH; 0.02 and 0.03%) and sodium azide (SA; 0.01 and 0.02%) to develop M1 seed. The M2 was screened against two herbicides including Ally Max 28.6% SG (X = 34.58 g/ha and 1.5X = 51.87 g/ha) and Atlantis 3.6% WG (X = 395.2 g/ha and 1.5X = 592.8 g/ha) using the following three screening methods: post plant emergence (PPE), pre-plant incorporation (PPI) and seed priming (SP). Data were recorded on survival index and survival percentage from each experimental unit of every population. Plants in all populations were categorized following their reaction to herbicides. The newly developed populations showed greater variation for herbicide resistance when compared to their progenitors. Phenotypic traits were significantly reduced in all the screening environments. Overall, 671 herbicide resistant mutants were selected from all testing environments. The seeds from selected plants were re-mutagenized at 150 Gy of gamma radiation and evaluated against higher dose of herbicides. This allowed selection of 134 herbicide resistant mutants. The selected mutants are useful germplasm for herbicide resistance breeding of lentil. PMID:28196091

Pre-breeding of lentil (Lens culinaris Medik.) for herbicide resistance through seed mutagenesis.

PubMed

Rizwan, Muhammad; Aslam, Muhammad; Asghar, Muhammad Jawad; Abbas, Ghulam; Shah, Tariq Mahmud; Shimelis, Hussein

2017-01-01

Lentil is a poor competitor of weeds and its sensitivity to herbicides is a major hurdle for large scale production. The present study was conducted to select herbicide resistant lentil genotypes through seed mutagenesis. Seeds of three advanced lentil genotypes (LPP 11001, LPP 11100 and LPP 11116) were treated with two different concentrations of ethyl methanesulfonate (EMS; 0.1 and 0.2%), hydrazine hydrate (HH; 0.02 and 0.03%) and sodium azide (SA; 0.01 and 0.02%) to develop M1 seed. The M2 was screened against two herbicides including Ally Max 28.6% SG (X = 34.58 g/ha and 1.5X = 51.87 g/ha) and Atlantis 3.6% WG (X = 395.2 g/ha and 1.5X = 592.8 g/ha) using the following three screening methods: post plant emergence (PPE), pre-plant incorporation (PPI) and seed priming (SP). Data were recorded on survival index and survival percentage from each experimental unit of every population. Plants in all populations were categorized following their reaction to herbicides. The newly developed populations showed greater variation for herbicide resistance when compared to their progenitors. Phenotypic traits were significantly reduced in all the screening environments. Overall, 671 herbicide resistant mutants were selected from all testing environments. The seeds from selected plants were re-mutagenized at 150 Gy of gamma radiation and evaluated against higher dose of herbicides. This allowed selection of 134 herbicide resistant mutants. The selected mutants are useful germplasm for herbicide resistance breeding of lentil.

Effects of Paraquat Ban on Herbicide Poisoning-Related Mortality.

PubMed

Ko, Dong Ryul; Chung, Sung Phil; You, Je Sung; Cho, Soohyung; Park, Yongjin; Chun, Byeongjo; Moon, Jeongmi; Kim, Hyun; Kim, Yong Hwan; Kim, Hyun Jin; Lee, Kyung Woo; Choi, SangChun; Park, Junseok; Park, Jung Soo; Kim, Seung Whan; Seo, Jeong Yeol; Park, Ha Young; Kim, Su Jin; Kang, Hyunggoo; Hong, Dae Young; Hong, Jung Hwa

2017-07-01

In Korea, registration of paraquat-containing herbicides was canceled in November 2011, and sales thereof were completely banned in November 2012. We evaluated the effect of the paraquat ban on the epidemiology and mortality of herbicide-induced poisoning. This retrospective study analyzed patients treated for herbicide poisoning at 17 emergency departments in South Korea between January 2010 and December 2014. The overall and paraquat mortality rates were compared pre- and post-ban. Factors associated with herbicide mortality were evaluated using logistic analysis. To determine if there were any changes in the mortality rates before and after the paraquat sales ban and the time point of any such significant changes in mortality, R software, version 3.0.3 (package, bcp) was used to perform a Bayesian change point analysis. We enrolled 2257 patients treated for herbicide poisoning (paraquat=46.8%). The overall and paraquat poisoning mortality rates were 40.6% and 73.0%, respectively. The decreased paraquat poisoning mortality rate (before, 75% vs. after, 67%, p=0.014) might be associated with increased intentionality. The multivariable logistic analysis revealed the paraquat ban as an independent predictor that decreased herbicide poisoning mortality (p=0.035). There were two major change points in herbicide mortality rates, approximately 3 months after the initial paraquat ban and 1 year after complete sales ban. This study suggests that the paraquat ban decreased intentional herbicide ingestion and contributed to lowering herbicide poisoning-associated mortality. The change point analysis suggests a certain timeframe was required for the manifestation of regulatory measures outcomes. © Copyright: Yonsei University College of Medicine 2017

Possible source term of high concentrations of mecoprop-p in leachate and water quality: impact of climate change, public use and disposal.

PubMed

Idowu, I A; Alkhaddar, R M; Atherton, W

2014-08-01

Mecoprop-p herbicide is often found in wells and water abstractions in many areas around Europe, the UK inclusive. There is a growing environmental and public health concern about mecoprop-p herbicide pollution in ground and surface water in England. Reviews suggest that extensive work has been carried out on the contribution of mecoprop-p herbicides from agricultural use whilst more work needs to be carried out on the contribution of mecoprop-p herbicide from non-agricultural use. The study covers two landfill sites in Weaver/Gowy Catchment. Mecoprop-p herbicide concentrations in the leachate quality range between 0.06 and 290 microg l1 in cells. High concentration ofmecoprop-p herbicide in the leachate quality suggests that there is a possible source term in the waste stream. This paper addresses the gap by exploring possible source terms of mecoprop-p herbicide contamination on landfill sites and evaluates the impact of public purchase, use and disposal alongside climate change on seasonal variations in mecoprop-p concentrations. Mecoprop-p herbicide was found to exceed the EU drinking water quality standards at the unsaturated zone/aquifer with observed average concentrations ranging between 0.005 and 7.96 microg l1. A route map for mecoprop-p herbicide source term contamination is essential for mitigation and pollution management with emphasis on both consumer and producer responsibility towards use of mecoprop-p product. In addition, improvement in data collection on mecoprop-p concentrations and detailed seasonal herbicide sales for non-agricultural purposes are needed to inform the analysis and decision process.

Laboratory study on leachability of five herbicides in South Australian soils.

PubMed

Ying, G G; Williams, B

2000-03-01

Norflurazon, oxadiazon, oxyfluorfen, trifluralin and simazine are herbicides widely used in the vineyards of the Barossa Valley, South Australia. The leaching behaviour of norflurazon, oxadiazon, oxyfluorfen and trifluralin was investigated on four key soils in the Barossa Valley. Leaching potential on packed soil columns and actual mobility using intact soil columns were investigated. On the packed soil columns, norflurazon was the most leachable herbicide. More of the herbicides were detected in the leachates from the sandy soils (Mountadam and Nuriootpa) than from the clayey soils (Lyndoch and Tanunda). Organic matter is generally low in soils in the Barossa region. Porosity and saturated conductivity significantly affect herbicide movement and in the sandy Mountadam and Nuriootpa soils, the water flux is greater than for the higher clay content Lyndoch and Tanunda soils. Increasing the time interval between herbicide application and the incidence of "rainfall" reduced the amounts of herbicides found in the leachates. The use of intact soil columns and including simazine for comparison showed that both norflurazon and simazine were present in the leachates. Simazine was the first herbicide to appear in leachates. Sectioning of the intact soil columns after leaching clearly demonstrated that norflurazon and simazine reached the bottom of the soil columns for all soils studied. Greater amounts of norflurazon were retained in the soil columns compared with simazine. The other herbicides were mostly retained in the initial sections of the soil columns.

Herbicide impact on the growth and reproduction of characteristic and rare arable weeds of winter cereal fields.

PubMed

Rotchés-Ribalta, Roser; Boutin, Céline; Blanco-Moreno, José M; Carpenter, David; Sans, F Xavier

2015-07-01

The decline of arable species characteristic of winter cereal fields has often been attributed to different factors related to agricultural intensification but most importantly to herbicide use. Herbicide phytotoxicity is most frequently assessed using short-term endpoints, primarily aboveground biomass. However, short-term sensitivity is usually not sufficient to detect actual effects because plants may or may not recover over time following sublethal herbicide exposures. Therefore, it is important to assess the long-term effects of herbicide applications. Annual species rely on renewable seed production to ensure their persistence; hence, assessment of herbicide sensitivity is more accurately estimated through effects on reproduction. Here we aim to assess the phytotoxicity of two commonly used herbicides: tribenuron and 2,4-D on eight plant species belonging to four families, each with one rare and one more common species. Specifically we examined the pattern of sensitivity using short-term and long-term endpoints (total aboveground biomass, total seed biomass and number of seeds) of these species; we determined the levels of and time to recovery in terms of stem length and fruit number, and assessed whether their rarity relates to their sensitivity to herbicide application. Our results suggest that although differences in herbicide sensitivity are not a direct cause of rarity for all species, it may be an important driver of declining arable plants.

Intensive herbicide use has selected for constitutively elevated levels of stress-responsive mRNAs and proteins in multiple herbicide-resistant Avena fatua L.

PubMed

Keith, Barbara K; Burns, Erin E; Bothner, Brian; Carey, Charles C; Mazurie, Aurélien J; Hilmer, Jonathan K; Biyiklioglu, Sezgi; Budak, Hikmet; Dyer, William E

2017-11-01

Intensive use of herbicides has led to the evolution of two multiple herbicide-resistant (MHR) Avena fatua (wild oat) populations in Montana that are resistant to members of all selective herbicide families available for A. fatua control in US small grain crops. We used transcriptome and proteome surveys to compare constitutive changes in MHR and herbicide-susceptible (HS) plants associated with non-target site resistance. Compared to HS plants, MHR plants contained constitutively elevated levels of differentially expressed genes (DEGs) with functions in xenobiotic catabolism, stress response, redox maintenance and transcriptional regulation that are similar to abiotic stress-tolerant phenotypes. Proteome comparisons identified similarly elevated proteins including biosynthetic and multifunctional enzymes in MHR plants. Of 25 DEGs validated by RT-qPCR assay, differential regulation of 21 co-segregated with flucarbazone-sodium herbicide resistance in F 3 families, and a subset of 10 of these were induced or repressed in herbicide-treated HS plants. Although the individual and collective contributions of these DEGs and proteins to MHR remain to be determined, our results support the idea that intensive herbicide use has selected for MHR populations with altered, constitutively regulated patterns of gene expression that are similar to those in abiotic stress-tolerant plants. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Enantioselective Phytotoxicity and the Relative Mechanism of Current Chiral Herbicides.

PubMed

Wang, Cui; Lu, Dezhao; Yang, Jinhuan; Xu, Yingling; Gong, Chenxue; Li, Zhuoyu

2017-01-01

Regardless of the achievable of chiral switch, most of the chiral nature agrochemical is still sold as racemate or enantiomer-enriched pesticides. Herbicides, accounted for a large proportion in pesticide market, are of great concern due to the frequent occurrence in environment and the structure selective phyto-biochemical impact on plants. We give a systematic search on the literature database and included approximately 50 papers which were related to the review. We do careful categories for the chiral herbicides according to their structure and listed out the acute phytotoxicity endpoints. The potential mechanism for the enantioselective toxicity was concluded into 5 main points. The enantiomer-specific toxicity on plant growth and flowers are limited on phenoxyalkanoic acid herbicide, aryloxyphenoxypropanoic acid, imidazolinone herbicide, and acetamide pesticide. Data available on the potential mechanism explanation of enantioselective phytotoxicity has been concerned on the genetic transcription, oxidative stress, and photosynthesis disruption, etc. A comparison between the two enantiomers' enantioselective effects identified an organ-specific and species-specific phenomenon for several herbicides. Moreover, a more herbicidal activity enantiomer is also displayed the more toxicity than its antipode. The review elucidated a paucity of information on the enantioselective effect research on various types of plants at the different life stages. It appealed us to conduct a more holistic approach to balance the benefit between herbicidal activity and phytotoxicity when try to develop an enantio-pure herbicide.

The Effect of Four Herbicides on the Survival and Growth of Nine Hardwood Species

Treesearch

Robert D. Williams; John E. Krajicek

1976-01-01

To learn more about the tolerance of hardwoods to herbicides, the survival and growth on nine hardwood species were compared in plots eitehr cultivated or treated with various herbicides applied at different rates, on prepared and unprepared ground, and before and after planting. Black walnut and white oak were very tolerant to all herbicides tested but American...

Stand dynamics of an old-field longleaf pine stand following herbicide application, poor survival, and subsequent replanting

Treesearch

E. David Dickens; Bryan C. McElvany; David J. Moorhead; Philip R. Torrance; P. Mark Crosby

2010-01-01

A study area in Emanuel County, GA installed to discern the effectiveness of various herbicides over newly planted (December 1999) longleaf pine (Pinus palustris Mill.) seedlings on an old-field site. Survival and height growth data after herbicide treatment indicate that the early (April 7, 2000) Oust+Velpar L herbicide treatment gave greater...

Forest worker exposure to airborne herbicide residues in smoke from prescribed fires in the Southern United States

Treesearch

Charles K. McMahon; Parshall B. Bush

1992-01-01

Occupational safety and health concerns have been raised in a number of southern states by workers conducting prescribed burns on forested lands treated with herbicides. Modeling assessments coupled with laboratory experiments have shown that the risk of airborne herbicide residues to workers is insignificant, even if the fire occurs immediately after herbicide...

The role of herbicides for enhancing productivity and conserving land for biodiversity in North America

Treesearch

Robert G. Wagner; Michael Newton; Elizabeth C. Cole; James H. Miller; Barry D. Shiver

2004-01-01

Herbicide technology has evolved with forest management in North America over the past 60 years and has become an integral part of modern forestry practice. Forest managers have prescribed herbicides to increase reforestation success and long-term timber yields. Wildlife managers and others interested in conserving biodi- versity, however, have often viewed herbicide...

Early Identification of Herbicide Stress in Soybean (Glycine max (L.) Merr.) Using Chlorophyll Fluorescence Imaging Technology

PubMed Central

Li, Hui; Wang, Pei; Weber, Jonas Felix; Gerhards, Roland

2017-01-01

Herbicides may damage soybean in conventional production systems. Chlorophyll fluorescence imaging technology has been applied to identify herbicide stress in weed species a few days after application. In this study, greenhouse experiments followed by field experiments at five sites were conducted to investigate if the chlorophyll fluorescence imaging is capable of identifying herbicide stress in soybean shortly after application. Measurements were carried out from emergence until the three-to-four-leaf stage of the soybean plants. Results showed that maximal photosystem II (PS II) quantum yield and shoot dry biomass was significantly reduced in soybean by herbicides compared to the untreated control plants. The stress of PS II inhibiting herbicides occurred on the cotyledons of soybean and plants recovered after one week. The stress induced by DOXP synthase-, microtubule assembly-, or cell division-inhibitors was measured from the two-leaf stage until four-leaf stage of soybean. We could demonstrate that the chlorophyll fluorescence imaging technology is capable for detecting herbicide stress in soybean. The system can be applied under both greenhouse and field conditions. This helps farmers to select weed control strategies with less phytotoxicity in soybean and avoid yield losses due to herbicide stress. PMID:29271905

Managing the evolution of herbicide resistance.

PubMed

Evans, Jeffrey A; Tranel, Patrick J; Hager, Aaron G; Schutte, Brian; Wu, Chenxi; Chatham, Laura A; Davis, Adam S

2016-01-01

Understanding and managing the evolutionary responses of pests and pathogens to control efforts is essential to human health and survival. Herbicide-resistant (HR) weeds undermine agricultural sustainability, productivity and profitability, yet the epidemiology of resistance evolution - particularly at landscape scales - is poorly understood. We studied glyphosate resistance in a major agricultural weed, Amaranthus tuberculatus (common waterhemp), using landscape, weed and management data from 105 central Illinois grain farms, including over 500 site-years of herbicide application records. Glyphosate-resistant (GR) A. tuberculatus occurrence was greatest in fields with frequent glyphosate applications, high annual rates of herbicide mechanism of action (MOA) turnover and few MOAs field(-1) year(-1) . Combining herbicide MOAs at the time of application by herbicide mixing reduced the likelihood of GR A. tuberculatus. These findings illustrate the importance of examining large-scale evolutionary processes at relevant spatial scales. Although measures such as herbicide mixing may delay GR or other HR weed traits, they are unlikely to prevent them. Long-term weed management will require truly diversified management practices that minimize selection for herbicide resistance traits. © 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Early Identification of Herbicide Stress in Soybean (Glycine max (L.) Merr.) Using Chlorophyll Fluorescence Imaging Technology.

PubMed

Li, Hui; Wang, Pei; Weber, Jonas Felix; Gerhards, Roland

2017-12-22

Herbicides may damage soybean in conventional production systems. Chlorophyll fluorescence imaging technology has been applied to identify herbicide stress in weed species a few days after application. In this study, greenhouse experiments followed by field experiments at five sites were conducted to investigate if the chlorophyll fluorescence imaging is capable of identifying herbicide stress in soybean shortly after application. Measurements were carried out from emergence until the three-to-four-leaf stage of the soybean plants. Results showed that maximal photosystem II (PS II) quantum yield and shoot dry biomass was significantly reduced in soybean by herbicides compared to the untreated control plants. The stress of PS II inhibiting herbicides occurred on the cotyledons of soybean and plants recovered after one week. The stress induced by DOXP synthase-, microtubule assembly-, or cell division-inhibitors was measured from the two-leaf stage until four-leaf stage of soybean. We could demonstrate that the chlorophyll fluorescence imaging technology is capable for detecting herbicide stress in soybean. The system can be applied under both greenhouse and field conditions. This helps farmers to select weed control strategies with less phytotoxicity in soybean and avoid yield losses due to herbicide stress.

Why was resistance to shorter-acting pre-emergence herbicides slower to evolve?

PubMed

Somerville, Gayle J; Powles, Stephen B; Walsh, Michael J; Renton, Michael

2017-05-01

Across several agricultural systems the evolution of herbicide resistance has occurred more rapidly to post-emergence than pre-emergence herbicides; however, the reasons for this are not clear. We used a new simulation model to investigate whether interactions between differences in order of application and weed cohorts affected could explain this historically observed difference between the herbicide groups. A 10 year delay in resistance evolution was predicted for a shorter-acting residual pre-emergence (cf. post-emergence), when all other parameters were identical. Differences in order of application between pre- and post-emergence herbicides had minimal effect on rates of resistance evolution when similar weed cohorts were affected. This modelling suggested that the historically observed lower levels of resistance to pre-emergence herbicides are most likely to be due to the smaller number of weed cohorts affected by many pre-emergence herbicides. The lower number of weed cohorts affected by pre-emergence herbicides necessitated the use of additional, effective control measures, thereby reducing resistance evolution. This study highlights the advantages of applying multiple control measures to each weed cohort. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Herbicide cycling has diverse effects on evolution of resistance in Chlamydomonas reinhardtii

PubMed Central

Lagator, Mato; Vogwill, Tom; Colegrave, Nick; Neve, Paul

2013-01-01

Cycling pesticides has been proposed as a means of retarding the evolution of resistance, but its efficacy has rarely been empirically tested. We evolved populations of Chlamydomonas reinhardtii in the presence of three herbicides: atrazine, glyphosate and carbetamide. Populations were exposed to a weekly, biweekly and triweekly cycling between all three pairwise combinations of herbicides and continuously to each of the three herbicides. We explored the impacts of herbicide cycling on the rate of resistance evolution, the level of resistance selected, the cost of resistance and the degree of generality (cross-resistance) observed. Herbicide cycling resulted in a diversity of outcomes: preventing evolution of resistance for some combinations of herbicides, having no impacts for others and increasing rates of resistance evolution in some instances. Weekly cycling of atrazine and carbetamide resulted in selection of a generalist population. This population had a higher level of resistance, and this generalist resistance was associated with a cost. The level of resistance selected did not vary amongst other regimes. Costs of resistance were generally highest when cycling was more frequent. Our data suggest that the effects of herbicide cycling on the evolution of resistance may be more complex and less favourable than generally assumed. PMID:23467494

Resistance to herbicides caused by single amino acid mutations in acetyl-CoA carboxylase in resistant populations of grassy weeds.

PubMed

Jang, SoRi; Marjanovic, Jasmina; Gornicki, Piotr

2013-03-01

Eleven spontaneous mutations of acetyl-CoA carboxylase have been identified in many herbicide-resistant populations of 42 species of grassy weeds, hampering application of aryloxyphenoxypropionate, cyclohexadione and phenylpyrazoline herbicides in agriculture. IC(50) shifts (resistance indices) caused by herbicide-resistant mutations were determined using a recombinant yeast system that allows comparison of the effects of single amino acid mutations in the same biochemical background, avoiding the complexity inherent in the in planta experiments. The effect of six mutations on the sensitivity of acetyl-CoA carboxylase to nine herbicides representing the three chemical classes was studied. A combination of partially overlapping binding sites of the three classes of herbicides and the structure of their variable parts explains cross-resistance among and between the three classes of inhibitors, as well as differences in their specificity. Some degree of resistance was detected for 51 of 54 herbicide/mutation combinations. Introduction of new herbicides targeting acetyl-CoA carboxylase will depend on their ability to overcome the high degree of cross-resistance already existing in weed populations. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Effects of herbicides on Behr's metalmark butterfly, a surrogate species for the endangered butterfly, Lange's metalmark.

PubMed

Stark, John D; Chen, Xue Dong; Johnson, Catherine S

2012-05-01

Lange's metalmark butterfly, Apodemia mormo langei Comstock, is in danger of extinction due to loss of habitat caused by invasive exotic plants which are eliminating its food, naked stem buckwheat. Herbicides are being used to remove invasive weeds from the dunes; however, little is known about the potential effects of herbicides on butterflies. To address this concern we evaluated potential toxic effects of three herbicides on Behr's metalmark, a close relative of Lange's metalmark. First instars were exposed to recommended field rates of triclopyr, sethoxydim, and imazapyr. Life history parameters were recorded after exposure. These herbicides reduced the number of adults that emerged from pupation (24-36%). Each herbicide has a different mode of action. Therefore, we speculate that effects are due to inert ingredients or indirect effects on food plant quality. If these herbicides act the same in A. mormo langei, they may contribute to the decline of this species. Copyright © 2012 Elsevier Ltd. All rights reserved.

Treatment by glyphosate-based herbicide alters life history parameters of the rose-grain aphid Metopolophium dirhodum

NASA Astrophysics Data System (ADS)

Saska, Pavel; Skuhrovec, Jiří; Lukáš, Jan; Chi, Hsin; Tuan, Shu-Jen; Honěk, Alois

2016-06-01

Glyphosate is the number one herbicide in the world. We investigated the sub-lethal effects of this herbicide on the aphid Metopolophium dirhodum (Walker), using an age-stage, two-sex life table approach. Three concentrations of the herbicide (low - 33.5, medium - 66.9 and high - 133.8 mmol dm-3 of active ingredient) and distilled water as the control were used. The LC50 of the IPA salt of glyphosate on M. dirhodum was equivalent to 174.9 mmol dm-3 of the active ingredient (CI95: 153.0, 199.0). The population parameters were significantly negatively affected by herbicide application, and this negative effect was progressive with the increasing concentration of the herbicide. A difference of two orders of magnitude existed in the predicted population development of M. dirhodum between the high concentration of the herbicide and the control. This is the first study that comprehensively documents such a negative effect on the population of an herbivorous insect.

Treatment by glyphosate-based herbicide alters life history parameters of the rose-grain aphid Metopolophium dirhodum

PubMed Central

Saska, Pavel; Skuhrovec, Jiří; Lukáš, Jan; Chi, Hsin; Tuan, Shu-Jen; Honěk, Alois

2016-01-01

Glyphosate is the number one herbicide in the world. We investigated the sub-lethal effects of this herbicide on the aphid Metopolophium dirhodum (Walker), using an age-stage, two-sex life table approach. Three concentrations of the herbicide (low - 33.5, medium - 66.9 and high - 133.8 mmol dm−3 of active ingredient) and distilled water as the control were used. The LC50 of the IPA salt of glyphosate on M. dirhodum was equivalent to 174.9 mmol dm−3 of the active ingredient (CI95: 153.0, 199.0). The population parameters were significantly negatively affected by herbicide application, and this negative effect was progressive with the increasing concentration of the herbicide. A difference of two orders of magnitude existed in the predicted population development of M. dirhodum between the high concentration of the herbicide and the control. This is the first study that comprehensively documents such a negative effect on the population of an herbivorous insect. PMID:27302015

Herbicide contamination and the potential impact to seagrass meadows in Hervey Bay, Queensland, Australia.

PubMed

McMahon, Kathryn; Bengtson Nash, Susan; Eaglesham, Geoff; Müller, Jochen F; Duke, Norman C; Winderlich, Steve

2005-01-01

Low concentrations of herbicides (up to 70 ng l(-1)), chiefly diuron (up to 50 ng l(-1)) were detected in surface waters associated with inter-tidal seagrass meadows of Zostera muelleri in Hervey Bay, south-east Queensland, Australia. Diuron and atrazine (up to 1.1 ng g(-1) dry weight of sediment) were detected in the sediments of these seagrass meadows. Concentration of the herbicides diuron, simazine and atrazine increased in surface waters associated with seagrass meadows during moderate river flow events indicating herbicides were washed from the catchment to the marine environment. Maximum herbicide concentration (sum of eight herbicides) in the Mary River during a moderate river flow event was 4260 ng l(-1). No photosynthetic stress was detected in seagrass in this study during low river flow. However, with moderate river flow events, nearshore seagrasses are at risk of being exposed to concentrations of herbicides that are known to inhibit photosynthesis.

Discrimination of herbicide-resistant kochia with hyperspectral imaging

NASA Astrophysics Data System (ADS)

Nugent, Paul W.; Shaw, Joseph A.; Jha, Prashant; Scherrer, Bryan; Donelick, Andrew; Kumar, Vipan

2018-01-01

A hyperspectral imager was used to differentiate herbicide-resistant versus herbicide-susceptible biotypes of the agronomic weed kochia, in different crops in the field at the Southern Agricultural Research Center in Huntley, Montana. Controlled greenhouse experiments showed that enough information was captured by the imager to classify plants as either a crop, herbicide-susceptible or herbicide-resistant kochia. The current analysis is developing an algorithm that will work in more uncontrolled outdoor situations. In overcast conditions, the algorithm correctly identified dicamba-resistant kochia, glyphosate-resistant kochia, and glyphosate- and dicamba-susceptible kochia with 67%, 76%, and 80% success rates, respectively.

Weed control changes and genetically modified herbicide tolerant crops in the USA 1996–2012

PubMed Central

Brookes, Graham

2014-01-01

Crops that have been genetically modified (GM) to be tolerant to herbicides have been widely grown in the USA since 1996. The rapid and widespread adoption of this technology reflects the important economic and environmental benefits that farmers have derived from its use (equal to $21.7 billion additional farm income and a 225 million kg reduction in herbicide active ingredient use 1996–2012). During this time, weed control practices in these crops relative to the ‘conventional alternative’ have evolved to reflect experience of using the technology, the challenges that have arisen and the increasing focus in recent years on developing sustainable production systems. This paper examines the evidence on the changing nature of herbicides used with these crops and in particular how farmers addressed the challenge of weed resistance. The evidence shows that use of the technology has resulted in a net reduction in both the amount of herbicide used and the associated environmental impact, as measured by the EIQ indicator when compared to what can reasonably be expected if the area planted to GM HT crops reverted to conventional production methods. It also facilitated many farmers being able to derive the economic and environmental benefits associated with switching from a plough-based to a no tillage or conservation tillage production system. In terms of herbicide use, the technology has also contributed to a change the profile of herbicides used. A broad range of, mostly selective herbicides has been replaced by one or 2 broad-spectrum herbicides (mostly glyphosate) used in conjunction with one or 2 other (complementary) herbicides. Since the mid-2000s, the average amount of herbicide applied and the associated environmental load, as measured by the EIQ indicator, have increased on both GM HT and conventional crops. A primary reason for these changes has been increasing incidence of weed species developing populations resistant to herbicides and increased awareness of the consequences of relying on a single or very limited number of herbicides for weed control. As a result, growers of GM HT crops have become much more proactive and diversified in their weed management programs in line with weed scientist recommendations and now include other herbicides (with different and complementary modes of action) in combination with glyphosate, even where instances of weed resistance to glyphosate have not been found. The willingness to proactively diversity weed management systems in the GM HT crops is also influenced by a desire to maintain effective weed control and hence continue to enjoy the benefits of no tillage and conservation tillage. Nevertheless, despite the increase in herbicide use in recent years, the use of GM HT technology continues to deliver significant economic and environmental gains to US farmers. PMID:25523177

Weed control changes and genetically modified herbicide tolerant crops in the USA 1996-2012.

PubMed

Brookes, Graham

2014-01-01

Crops that have been genetically modified (GM) to be tolerant to herbicides have been widely grown in the USA since 1996. The rapid and widespread adoption of this technology reflects the important economic and environmental benefits that farmers have derived from its use (equal to $21.7 billion additional farm income and a 225 million kg reduction in herbicide active ingredient use 1996-2012). During this time, weed control practices in these crops relative to the 'conventional alternative' have evolved to reflect experience of using the technology, the challenges that have arisen and the increasing focus in recent years on developing sustainable production systems. This paper examines the evidence on the changing nature of herbicides used with these crops and in particular how farmers addressed the challenge of weed resistance. The evidence shows that use of the technology has resulted in a net reduction in both the amount of herbicide used and the associated environmental impact, as measured by the EIQ indicator when compared to what can reasonably be expected if the area planted to GM HT crops reverted to conventional production methods. It also facilitated many farmers being able to derive the economic and environmental benefits associated with switching from a plough-based to a no tillage or conservation tillage production system. In terms of herbicide use, the technology has also contributed to a change the profile of herbicides used. A broad range of, mostly selective herbicides has been replaced by one or 2 broad-spectrum herbicides (mostly glyphosate) used in conjunction with one or 2 other (complementary) herbicides. Since the mid-2000s, the average amount of herbicide applied and the associated environmental load, as measured by the EIQ indicator, have increased on both GM HT and conventional crops. A primary reason for these changes has been increasing incidence of weed species developing populations resistant to herbicides and increased awareness of the consequences of relying on a single or very limited number of herbicides for weed control. As a result, growers of GM HT crops have become much more proactive and diversified in their weed management programs in line with weed scientist recommendations and now include other herbicides (with different and complementary modes of action) in combination with glyphosate, even where instances of weed resistance to glyphosate have not been found. The willingness to proactively diversity weed management systems in the GM HT crops is also influenced by a desire to maintain effective weed control and hence continue to enjoy the benefits of no tillage and conservation tillage. Nevertheless, despite the increase in herbicide use in recent years, the use of GM HT technology continues to deliver significant economic and environmental gains to US farmers.

Non-target effects of a glyphosate-based herbicide on Common toad larvae (Bufo bufo, Amphibia) and associated algae are altered by temperature.

PubMed

Baier, Fabian; Gruber, Edith; Hein, Thomas; Bondar-Kunze, Elisabeth; Ivanković, Marina; Mentler, Axel; Brühl, Carsten A; Spangl, Bernhard; Zaller, Johann G

2016-01-01

Glyphosate-based herbicides are the most widely used pesticides in agriculture, horticulture, municipalities and private gardens that can potentially contaminate nearby water bodies inhabited by amphibians and algae. Moreover, the development and diversity of these aquatic organisms could also be affected by human-induced climate change that might lead to more periods with extreme temperatures. However, to what extent non-target effects of these herbicides on amphibians or algae are altered by varying temperature is not well known. We studied effects of five concentrations of the glyphosate-based herbicide formulation Roundup PowerFlex (0, 1.5, 3, 4 mg acid equivalent glyphosate L -1 as a one time addition and a pulse treatment of totally 4 mg a.e. glyphosate L -1 ) on larval development of Common toads ( Bufo bufo , L.; Amphibia: Anura) and associated algae communities under two temperature regimes (15 vs. 20 °C). Herbicide contamination reduced tail growth (-8%), induced the occurrence of tail deformations (i.e. lacerated or crooked tails) and reduced algae diversity (-6%). Higher water temperature increased tadpole growth (tail and body length (tl/bl) +66%, length-to-width ratio +4%) and decreased algae diversity (-21%). No clear relation between herbicide concentrations and tadpole growth or algae density or diversity was observed. Interactive effects of herbicides and temperature affected growth parameters, tail deformation and tadpole mortality indicating that the herbicide effects are temperature-dependent. Remarkably, herbicide-temperature interactions resulted in deformed tails in 34% of all herbicide treated tadpoles at 15 °C whereas no tail deformations were observed for the herbicide-free control at 15 °C or any tadpole at 20 °C; herbicide-induced mortality was higher at 15 °C but lower at 20 °C. These herbicide- and temperature-induced changes may have decided effects on ecological interactions in freshwater ecosystems. Although no clear dose-response effect was seen, the presence of glyphosate was decisive for an effect, suggesting that the lowest observed effect concentration (LOEC) in our study was 1.5 mg a.e. glyphosate L -1 water. Overall, our findings also question the relevance of pesticide risk assessments conducted at standard temperatures.

Non-target effects of a glyphosate-based herbicide on Common toad larvae (Bufo bufo, Amphibia) and associated algae are altered by temperature

PubMed Central

Baier, Fabian; Gruber, Edith; Bondar-Kunze, Elisabeth; Ivanković, Marina; Mentler, Axel; Brühl, Carsten A.; Spangl, Bernhard

2016-01-01

Background Glyphosate-based herbicides are the most widely used pesticides in agriculture, horticulture, municipalities and private gardens that can potentially contaminate nearby water bodies inhabited by amphibians and algae. Moreover, the development and diversity of these aquatic organisms could also be affected by human-induced climate change that might lead to more periods with extreme temperatures. However, to what extent non-target effects of these herbicides on amphibians or algae are altered by varying temperature is not well known. Methods We studied effects of five concentrations of the glyphosate-based herbicide formulation Roundup PowerFlex (0, 1.5, 3, 4 mg acid equivalent glyphosate L−1 as a one time addition and a pulse treatment of totally 4 mg a.e. glyphosate L−1) on larval development of Common toads (Bufo bufo, L.; Amphibia: Anura) and associated algae communities under two temperature regimes (15 vs. 20 °C). Results Herbicide contamination reduced tail growth (−8%), induced the occurrence of tail deformations (i.e. lacerated or crooked tails) and reduced algae diversity (−6%). Higher water temperature increased tadpole growth (tail and body length (tl/bl) +66%, length-to-width ratio +4%) and decreased algae diversity (−21%). No clear relation between herbicide concentrations and tadpole growth or algae density or diversity was observed. Interactive effects of herbicides and temperature affected growth parameters, tail deformation and tadpole mortality indicating that the herbicide effects are temperature-dependent. Remarkably, herbicide-temperature interactions resulted in deformed tails in 34% of all herbicide treated tadpoles at 15 °C whereas no tail deformations were observed for the herbicide-free control at 15 °C or any tadpole at 20 °C; herbicide-induced mortality was higher at 15 °C but lower at 20 °C. Discussion These herbicide- and temperature-induced changes may have decided effects on ecological interactions in freshwater ecosystems. Although no clear dose-response effect was seen, the presence of glyphosate was decisive for an effect, suggesting that the lowest observed effect concentration (LOEC) in our study was 1.5 mg a.e. glyphosate L−1 water. Overall, our findings also question the relevance of pesticide risk assessments conducted at standard temperatures. PMID:27833808

Herbicide Safeners Decrease Sensitivity to Herbicides Inhibiting Acetolactate-Synthase and Likely Activate Non-Target-Site-Based Resistance Pathways in the Major Grass Weed Lolium sp. (Rye-Grass)

PubMed Central

Duhoux, Arnaud; Pernin, Fanny; Desserre, Diane; Délye, Christophe

2017-01-01

Herbicides are currently pivotal to control weeds and sustain food security. Herbicides must efficiently kill weeds while being as harmless as possible for crops, even crops taxonomically close to weeds. To increase their selectivity toward crops, some herbicides are sprayed in association with safeners that are bioactive compounds exacerbating herbicide-degrading pathways reputedly specifically in crops. However, exacerbated herbicide metabolism is also a key mechanism underlying evolved non-target-site-based resistance to herbicides (NTSR) in weeds. This raised the issue of a possible role of safeners on NTSR evolution in weeds. We investigated a possible effect of the respective field rates of the two broadly used safeners cloquintocet-mexyl and mefenpyr-diethyl on the sensitivity of the troublesome global weed Lolium sp. (rye-grass) to the major herbicides inhibiting acetolactate-synthase (ALS) pyroxsulam and iodosulfuron + mesosulfuron, respectively. Three Lolium sp. populations were studied in three series of experiments. The first experiment series compared the frequencies of plants surviving application of each herbicide alone or in association with its safener. Safener co-application caused a net increase ranging from 5.0 to 46.5% in the frequency of plants surviving the field rate of their associated herbicide. In a second series of experiments, safener effect was assessed on individual plant sensitivity using vegetative propagation. A reduction in sensitivity to pyroxsulam and to iodosulfuron + mesosulfuron was observed for 44.4 and 11.1% of the plants in co-treatment with cloquintocet-mexyl and mefenpyr-diethyl, respectively. A third series of experiments investigated safener effect on the expression level of 19 Lolium sp. NTSR marker genes. Safeners showed an enhancing effect on the expression level of 10 genes. Overall, we demonstrated that cloquintocet-mexyl and mefenpyr-diethyl both reduced the sensitivity of Lolium sp. to their associated ALS-inhibiting herbicide and most likely exacerbated herbicide-degrading secondary metabolism pathways. This suggests that genetic variation for safener response is present in Lolium sp. Thus, a possible, uninvestigated way to NTSR evolution could be selection for increased responsiveness to safener action. Delivering safeners exclusively to the crop could mitigate the risk for NTSR evolution in weeds. PMID:28848566

Herbicide Safeners Decrease Sensitivity to Herbicides Inhibiting Acetolactate-Synthase and Likely Activate Non-Target-Site-Based Resistance Pathways in the Major Grass Weed Lolium sp. (Rye-Grass).

PubMed

Duhoux, Arnaud; Pernin, Fanny; Desserre, Diane; Délye, Christophe

2017-01-01

Herbicides are currently pivotal to control weeds and sustain food security. Herbicides must efficiently kill weeds while being as harmless as possible for crops, even crops taxonomically close to weeds. To increase their selectivity toward crops, some herbicides are sprayed in association with safeners that are bioactive compounds exacerbating herbicide-degrading pathways reputedly specifically in crops. However, exacerbated herbicide metabolism is also a key mechanism underlying evolved non-target-site-based resistance to herbicides (NTSR) in weeds. This raised the issue of a possible role of safeners on NTSR evolution in weeds. We investigated a possible effect of the respective field rates of the two broadly used safeners cloquintocet-mexyl and mefenpyr-diethyl on the sensitivity of the troublesome global weed Lolium sp. (rye-grass) to the major herbicides inhibiting acetolactate-synthase (ALS) pyroxsulam and iodosulfuron + mesosulfuron, respectively. Three Lolium sp. populations were studied in three series of experiments. The first experiment series compared the frequencies of plants surviving application of each herbicide alone or in association with its safener. Safener co-application caused a net increase ranging from 5.0 to 46.5% in the frequency of plants surviving the field rate of their associated herbicide. In a second series of experiments, safener effect was assessed on individual plant sensitivity using vegetative propagation. A reduction in sensitivity to pyroxsulam and to iodosulfuron + mesosulfuron was observed for 44.4 and 11.1% of the plants in co-treatment with cloquintocet-mexyl and mefenpyr-diethyl, respectively. A third series of experiments investigated safener effect on the expression level of 19 Lolium sp. NTSR marker genes. Safeners showed an enhancing effect on the expression level of 10 genes. Overall, we demonstrated that cloquintocet-mexyl and mefenpyr-diethyl both reduced the sensitivity of Lolium sp. to their associated ALS-inhibiting herbicide and most likely exacerbated herbicide-degrading secondary metabolism pathways. This suggests that genetic variation for safener response is present in Lolium sp. Thus, a possible, uninvestigated way to NTSR evolution could be selection for increased responsiveness to safener action. Delivering safeners exclusively to the crop could mitigate the risk for NTSR evolution in weeds.

Occurrence and behavior of the herbicide Prometon in the hydrologic system

USGS Publications Warehouse

Capel, P.D.; Spexet, A.H.; Larson, S.J.

1999-01-01

Prometon, a triazine herbicide, is used for total vegetation control on industrial sites, on noncrop areas on farms, in and under asphalt, and to a small extent by homeowners. Prometon has often been detected in surface water and groundwater in studies reported in the literature, but its presence is seldom discussed, partly because of its infrequent inclusion on lists of herbicides used in either agricultural or urban areas. In recent large-scale studies by the U.S. Geological Survey, prometon has been the most commonly detected herbicide in surface water and groundwater in urban areas and the third and fourth most commonly detected herbicide in groundwater and surface water, respectively, in agricultural areas. It also has been detected in rain. The frequent detection of prometon in the environment is discussed in relation to its use practices and predicted environmental behavior. Prometon is compared to atrazine, a structurally similar agricultural triazine herbicide that is one of the most studied and most commonly detected herbicides found in the hydrologic environment. The environmental data presented here demonstrate the wide-scale occurrence of prometon in all components of the hydrologic system, particularly in the surface water and groundwater of urban areas.Prometon, a triazine herbicide, is used for total vegetation control on industrial sites, on noncrop areas on farms, in and under asphalt, and to a small extent by homeowners. Prometon has often been detected in surface water and groundwater in studies reported in the literature, but its presence is seldom discussed, partly because of its infrequent inclusion on lists of herbicides used in either agricultural or urban areas. In recent large-scale studies by the U.S. Geological Survey, prometon has been the most commonly detected herbicide in surface water and groundwater in urban areas and the third and fourth most commonly detected herbicide in groundwater and surface water, respectively, in agricultural areas. It also has been detected in rain. The frequent detection of prometon in the environment is discussed in relation to its use practices and predicted environmental behavior. Prometon is compared to atrazine, a structurally similar agricultural triazine herbicide that is one of the most studied and most commonly detected herbicides found in the hydrologic environment. The environmental data presented here demonstrate the wide-scale occurrence of prometon in all components of the hydrologic system, particularly in the surface water and groundwater of urban areas.

Ten-year response of a forest bird community to an operational herbicide-shelterwood treatment in Allegheny hardwoods

Treesearch

Scott H. Stoleson; Todd E. Ristau; David S. deCalesta; Stephen B. Horsley

2011-01-01

Use of herbicides in forestry to direct successional trajectories has raised concerns over possible direct or indirect effects on non-target organisms. We studied the response of forest birds to an operational application of glyphosate and sulfometuron methyl herbicides, using a randomized block design in which half of each 8 ha block received herbicide and the other...

Concentration of selected sulfonylurea, sulfonamide, and imidazolinone herbicides, other pesticides, and nutrients in 71 streams, 5 reservoir outflows, and 25 wells in the Midwestern United States, 1998

USGS Publications Warehouse

Battaglin, William A.; Furlong, Edward T.; Burkhardt, Mark R.

2001-01-01

Sulfonylurea (SU), sulfonamide (SA), and imidazolinone (IMI) herbicides are recently developed herbicides that function by inhibiting the action of a key plant enzyme, stopping plant growth, and eventually killing the plant. These compounds generally have low mammalian toxicity, but crop and non-crop plants demonstrate a wide range in sensitivity to SUs, SAs, and IMIs, with over a 10,000-fold difference in observed toxicity levels for some compounds. SUs, SAs, and IMIs are applied either pre- or post-emergence to crops commonly at 1/50th or less of the rate of other herbicides. Little is known about their occurrence, fate, or transport in surface water or ground water in the United States. To obtain information on the occurrence of SU, SA, and IMI herbicides in the Midwestern United States, 214 water samples were collected from 76 surface-water and 25 ground-water sites in 1998. These samples were analyzed for 16 SU, SA, and IMI herbicides by using highperformance liquid chromatography/mass spectrometry. Samples also were analyzed for 46 pesticides and pesticide degradation products and 13 herbicides and 10 herbicide degradates. At least 1 of the 16 SUs, SAs, or IMIs was detected at or above the method reporting limit of 0.010 microgram per liter (ug/L) in 83 percent of 133 stream samples. Imazethapyr was detected most frequently (69 percent of samples), followed by flumetsulam (65 percent of samples) and nicosulfuron (53 percent of samples). At least one SU, SA, or IMI herbicide was detected at or above the method reporting limit in 6 of 8 reservoir samples and 5 of 25 ground-water samples. SU, SA, and IMI herbicides occurred less frequently and at a fraction (often 1/50th or less) of the concentrations of other herbicides such as atrazine. Acetochlor, atrazine, cyanazine, and metolachlor were all detected in 95 percent or more of 136 stream samples.

[Effects of herbicide on grape leaf photosynthesis and nutrient storage].

PubMed

Tan, Wei; Wang, Hui; Zhai, Heng

2011-09-01

Selecting three adjacent vineyards as test objects, this paper studied the effects of applying herbicide in growth season on the leaf photosynthetic apparatus and branch nutrient storage of grape Kyoho (Vitis vinfrraxVitis labrusca). In the vineyards T1 and T2 where herbicide was applied in 2009, the net photosynthesis rate (Pa) of grape leaves had a significant decrease, as compared with that in vineyard CK where artificial weeding was implemented. The leaves at the fourth node in vineyard T1 and those at the sixth node in vineyard T2 had the largest decrement of Pn (40.5% and 32.1%, respectively). Herbicide had slight effects on the leaf stomatal conductance (Gs). In T1 where herbicide application was kept on with in 2010, the Pn, was still significantly lower than that in CK; while in T2 where artificial weeding was implemented in 2010, the Pn and Gs of top- and middle node leaves were slightly higher than those in T1, but the Pn was still lower than that in CK, showing the aftereffects of herbicide residual. The herbicide application in 2009 decreased the leaf maximum photochemical efficiency of PS II (Fv/Fm) and performance index (P1) while increased the relative variable fluorescence in the J step and K step, indicating the damage of electron transportation of PS II center and oxygen-evolving complex. Herbicide application decreased the pigment content of middle-node leaves in a dose-manner. Applying herbicide enhanced the leaf catalase and peroxidase activities significantly, increased the superoxide dismutase (SOD) activity of middle-node leaves, but decreased the SOD activity of top- and bottom node leaves. After treated with herbicide, the ascorbate peroxidase (APX) activity of middle- and bottom node leaves increased, but that of top-node leaves decreased. Herbicide treatment aggravated leaf lipid peroxidation, and reduced the soluble sugar, starch, free amino acids, and soluble protein storage in branches.

A novel rice cytochrome P450 gene, CYP72A31, confers tolerance to acetolactate synthase-inhibiting herbicides in rice and Arabidopsis.

PubMed

Saika, Hiroaki; Horita, Junko; Taguchi-Shiobara, Fumio; Nonaka, Satoko; Nishizawa-Yokoi, Ayako; Iwakami, Satoshi; Hori, Kiyosumi; Matsumoto, Takashi; Tanaka, Tsuyoshi; Itoh, Takeshi; Yano, Masahiro; Kaku, Koichiro; Shimizu, Tsutomu; Toki, Seiichi

2014-11-01

Target-site and non-target-site herbicide tolerance are caused by the prevention of herbicide binding to the target enzyme and the reduction to a nonlethal dose of herbicide reaching the target enzyme, respectively. There is little information on the molecular mechanisms involved in non-target-site herbicide tolerance, although it poses the greater threat in the evolution of herbicide-resistant weeds and could potentially be useful for the production of herbicide-tolerant crops because it is often involved in tolerance to multiherbicides. Bispyribac sodium (BS) is an herbicide that inhibits the activity of acetolactate synthase. Rice (Oryza sativa) of the indica variety show BS tolerance, while japonica rice varieties are BS sensitive. Map-based cloning and complementation tests revealed that a novel cytochrome P450 monooxygenase, CYP72A31, is involved in BS tolerance. Interestingly, BS tolerance was correlated with CYP72A31 messenger RNA levels in transgenic plants of rice and Arabidopsis (Arabidopsis thaliana). Moreover, Arabidopsis overexpressing CYP72A31 showed tolerance to bensulfuron-methyl (BSM), which belongs to a different class of acetolactate synthase-inhibiting herbicides, suggesting that CYP72A31 can metabolize BS and BSM to a compound with reduced phytotoxicity. On the other hand, we showed that the cytochrome P450 monooxygenase CYP81A6, which has been reported to confer BSM tolerance, is barely involved, if at all, in BS tolerance, suggesting that the CYP72A31 enzyme has different herbicide specificities compared with CYP81A6. Thus, the CYP72A31 gene is a potentially useful genetic resource in the fields of weed control, herbicide development, and molecular breeding in a broad range of crop species. © 2014 American Society of Plant Biologists. All Rights Reserved.

Effects of Sublethal Exposure to a Glyphosate-Based Herbicide Formulation on Metabolic Activities of Different Xenobiotic-Metabolizing Enzymes in Rats.

PubMed

Larsen, Karen; Najle, Roberto; Lifschitz, Adrián; Maté, María L; Lanusse, Carlos; Virkel, Guillermo L

2014-07-01

The activities of different xenobiotic-metabolizing enzymes in liver subcellular fractions from Wistar rats exposed to a glyphosate (GLP)-based herbicide (Roundup full II) were evaluated in this work. Exposure to the herbicide triggered protective mechanisms against oxidative stress (increased glutathione peroxidase activity and total glutathione levels). Liver microsomes from both male and female rats exposed to the herbicide had lower (45%-54%, P < 0.01) hepatic cytochrome P450 (CYP) levels compared to their respective control animals. In female rats, the hepatic 7-ethoxycoumarin O-deethylase (a general CYP-dependent enzyme activity) was 57% higher (P < 0.05) in herbicide-exposed compared to control animals. Conversely, this enzyme activity was 58% lower (P < 0.05) in male rats receiving the herbicide. Lower (P < 0.05) 7-ethoxyresorufin O-deethlyase (EROD, CYP1A1/2 dependent) and oleandomycin triacetate (TAO) N-demethylase (CYP3A dependent) enzyme activities were observed in liver microsomes from exposed male rats. Conversely, in females receiving the herbicide, EROD increased (123%-168%, P < 0.05), whereas TAO N-demethylase did not change. A higher (158%-179%, P < 0.01) benzyloxyresorufin O-debenzylase (a CYP2B-dependent enzyme activity) activity was only observed in herbicide-exposed female rats. In herbicide-exposed rats, the hepatic S-oxidation of methimazole (flavin monooxygenase dependent) was 49% to 62% lower (P < 0.001), whereas the carbonyl reduction of menadione (a cytosolic carbonyl reductase-dependent activity) was higher (P < 0.05). Exposure to the herbicide had no effects on enzymatic activities dependent on carboxylesterases, glutathione transferases, and uridinediphospho-glucuronosyltransferases. This research demonstrated certain biochemical modifications after exposure to a GLP-based herbicide. Such modifications may affect the metabolic fate of different endobiotic and xenobiotic substances. The pharmacotoxicological significance of these findings remains to be clarified. © The Author(s) 2014.

Global perspective of herbicide-resistant weeds.

PubMed

Heap, Ian

2014-09-01

Two hundred and twenty weed species have evolved resistance to one or more herbicides, and there are now 404 unique cases (species × site of action) of herbicide-resistant weeds globally. ALS inhibitor-resistant weeds account for about a third of all cases (133/404) and are particularly troublesome in rice and cereals. Although 71 weed species have been identified with triazine resistance, their importance has dwindled with the shift towards Roundup Ready® crops in the USA and the reduction of triazine usage in Europe. Forty-three grasses have evolved resistance to ACCase inhibitors, with the most serious cases being Avena spp., Lolium spp., Phalaris spp., Setaria spp. and Alopecurus myosuroides, infesting more than 25 million hectares of cereal production globally. Of the 24 weed species with glyphosate resistance, 16 have been found in Roundup Ready® cropping systems. Although Conyza canadensis is the most widespread glyphosate-resistant weed, Amaranthus palmeri and Amaranthus tuberculartus are the two most economically important glyphosate-resistant weeds because of the area they infest and the fact that these species have evolved resistance to numerous other herbicide sites of action, leaving growers with few herbicidal options for their control. The agricultural chemical industry has not brought any new herbicides with novel sites of action to market in over 30 years, making growers reliant on using existing herbicides in new ways. In addition, tougher registration and environmental regulations on herbicides have resulted in a loss of some herbicides, particularly in Europe. The lack of novel herbicide chemistries being brought to market combined with the rapid increase in multiple resistance in weeds threatens crop production worldwide. © 2013 Society of Chemical Industry.

Screening of photosynthetic pigments for herbicidal activity with a new computational molecular approach.

PubMed

Krishnaraj, R Navanietha; Chandran, Saravanan; Pal, Parimal; Berchmans, Sheela

2013-12-01

There is an immense interest among the researchers to identify new herbicides which are effective against the herbs without affecting the environment. In this work, photosynthetic pigments are used as the ligands to predict their herbicidal activity. The enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is a good target for the herbicides. Homology modeling of the target enzyme is done using Modeler 9.11 and the model is validated. Docking studies were performed with AutoDock Vina algorithm to predict the binding of the natural pigments such as β-carotene, chlorophyll a, chlorophyll b, phycoerythrin and phycocyanin to the target. β-carotene, phycoerythrin and phycocyanin have higher binding energies indicating the herbicidal activity of the pigments. This work reports a procedure to screen herbicides with computational molecular approach. These pigments will serve as potential bioherbicides in the future.

4-Hydroxyphenylpyruvate Dioxygenase Inhibitors: From Chemical Biology to Agrochemicals.

PubMed

Ndikuryayo, Ferdinand; Moosavi, Behrooz; Yang, Wen-Chao; Yang, Guang-Fu

2017-10-04

The development of new herbicides is receiving considerable attention to control weed biotypes resistant to current herbicides. Consequently, new enzymes are always desired as targets for herbicide discovery. 4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) is an enzyme engaged in photosynthetic activity and catalyzes the transformation of 4-hydroxyphenylpyruvic acid (HPPA) into homogentisic acid (HGA). HPPD inhibitors constitute a promising area of discovery and development of innovative herbicides with some advantages, including excellent crop selectivity, low application rates, and broad-spectrum weed control. HPPD inhibitors have been investigated for agrochemical interests, and some of them have already been commercialized as herbicides. In this review, we mainly focus on the chemical biology of HPPD, discovery of new potential inhibitors, and strategies for engineering transgenic crops resistant to current HPPD-inhibiting herbicides. The conclusion raises some relevant gaps for future research directions.

Herbicide-Resistant Crops: Utilities and Limitations for Herbicide-Resistant Weed Management

PubMed Central

2010-01-01

Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and cotton growers use to manage weeds. The use of GR crops continues to grow, but weeds are adapting to the common practice of using only glyphosate to control weeds. Growers using only a single mode of action to manage weeds need to change to a more diverse array of herbicidal, mechanical, and cultural practices to maintain the effectiveness of glyphosate. Unfortunately, the introduction of GR crops and the high initial efficacy of glyphosate often lead to a decline in the use of other herbicide options and less investment by industry to discover new herbicide active ingredients. With some exceptions, most growers can still manage their weed problems with currently available selective and HR crop-enabled herbicides. However, current crop management systems are in jeopardy given the pace at which weed populations are evolving glyphosate resistance. New HR crop technologies will expand the utility of currently available herbicides and enable new interim solutions for growers to manage HR weeds, but will not replace the long-term need to diversify weed management tactics and discover herbicides with new modes of action. This paper reviews the strengths and weaknesses of anticipated weed management options and the best management practices that growers need to implement in HR crops to maximize the long-term benefits of current technologies and reduce weed shifts to difficult-to-control and HR weeds. PMID:20586458

Climate change increases the risk of herbicide-resistant weeds due to enhanced detoxification.

PubMed

Matzrafi, Maor; Seiwert, Bettina; Reemtsma, Thorsten; Rubin, Baruch; Peleg, Zvi

2016-12-01

Global warming will increase the incidence of metabolism-based reduced herbicide efficacy on weeds and, therefore, the risk for evolution of non-target site herbicide resistance. Climate changes affect food security both directly and indirectly. Weeds are the major biotic factor limiting crop production worldwide, and herbicides are the most cost-effective way for weed management. Processes associated with climatic changes, such as elevated temperatures, can strongly affect weed control efficiency. Responses of several grass weed populations to herbicides that inhibit acetyl-CoA carboxylase (ACCase) were examined under different temperature regimes. We characterized the mechanism of temperature-dependent sensitivity and the kinetics of pinoxaden detoxification. The products of pinoxaden detoxification were quantified. Decreased sensitivity to ACCase inhibitors was observed under elevated temperatures. Pre-treatment with the cytochrome-P450 inhibitor malathion supports a non-target site metabolism-based mechanism of herbicide resistance. The first 48 h after herbicide application were crucial for pinoxaden detoxification. The levels of the inactive glucose-conjugated pinoxaden product (M5) were found significantly higher under high- than low-temperature regime. Under high temperature, a rapid elevation in the level of the intermediate metabolite (M4) was found only in pinoxaden-resistant plants. Our results highlight the quantitative nature of non-target-site resistance. To the best of our knowledge, this is the first experimental evidence for temperature-dependent herbicide sensitivity based on metabolic detoxification. These findings suggest an increased risk for the evolution of herbicide-resistant weeds under predicted climatic conditions.

Effects of the herbicides linuron and S-metolachlor on Perez's frog embryos.

PubMed

Quintaneiro, Carla; Soares, Amadeu M V M; Monteiro, Marta S

2018-03-01

Presence of pesticides in the environment and their possible effects on aquatic organisms are of great concern worldwide. The extensive use of herbicides in agricultural areas are one of the factors contributing to the known decline of amphibian populations. Thus, as non-target species, amphibians can be exposed in early life stages to herbicides in aquatic systems. In this context, this study aims to evaluate effects of increasing concentrations of two maize herbicides, linuron and S-metolachlor on embryos of the Perez' frog (Pelophylax perezi) during 192 h. Apical endpoints were determined for each herbicide: mortality, hatching rate, malformations and length. Frog embryos presented a LC 50 of 21 mg/l linuron and 37.5 mg/l S-metolachlor. Furthermore, sub-lethal concentrations of both herbicides affected normal embryonic development, delaying hatching, decreasing larvae length and causing several malformations. Length of larvae decreased with increasing concentrations of each herbicide, even at the lower concentrations tested. Malformations observed in larvae exposed to both herbicides were oedemas, spinal curvature and deformation, blistering and microphtalmia. Overall, these results highlight the need to assess adverse effects of xenobiotics to early life stages of amphibians regarding beside mortality the embryonic development, which could result in impairments at later stages. However, to unravel mechanisms involved in toxicity of these herbicides further studies regarding lower levels of biological organisation such as biochemical and genomic level should be performed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combining glyphosate with burning or mowing improves control of Yellow Bluestem (Bothriochloa ischaemum)

USGS Publications Warehouse

Robertson, S.; Hickman, Karen R.; Harmoney, Keith R.; Leslie,, David M.

2013-01-01

The invasive yellow bluestem (Bothriochloa ischaemum [L.] Keng) threatens native biodiversity, and its control is of interest to land managers involved in restoration of invaded grasslands. We used single, double, and triple applications of glyphosate (2.125 kg ai.ha-1.application-1) over the course of one growing season in combinations at different timings (early, middle, late season) with and without a mechanical treatment of mowing or burning to determine the most effective control method. One year after treatment, burning and mowing prior to a mid-season single or double early, middle, and/or late season herbicide application resulted in a similar level of control of yellow bluestem relative to a triple herbicide application, all of which had greater control relative to herbicide treatment alone. Reproductive tiller density and visual obstruction increased 2 yr after treatment with two herbicide treatments applied either early and middle season or early and late season, but it was prevented with burning and mowing prior to herbicide application. With the exception of three herbicide applications, combining burning or mowing with herbicide applications provided more effective control of yellow bluestem than any individual herbicide applications. Burning or mowing likely improves glyphosate effectiveness by altering the invasive grass structure so that plants are clear of standing dead and have shorter, active regrowth to enhance herbicide effectiveness. During restoration projects requiring control of invasive yellow bluestem, an effective management option is a combination of mechanical and chemical control.

Resistance to AHAS inhibitor herbicides: current understanding.

PubMed

Yu, Qin; Powles, Stephen B

2014-09-01

Acetohydroxyacid synthase (AHAS) inhibitor herbicides currently comprise the largest site-of-action group (with 54 active ingredients across five chemical groups) and have been widely used in world agriculture since they were first introduced in 1982. Resistance evolution in weeds to AHAS inhibitors has been rapid and identified in populations of many weed species. Often, evolved resistance is associated with point mutations in the target AHAS gene; however non-target-site enhanced herbicide metabolism occurs as well. Many AHAS gene resistance mutations can occur and be rapidly enriched owing to a high initial resistance gene frequency, simple and dominant genetic inheritance and lack of major fitness cost of the resistance alleles. Major advances in the elucidation of the crystal structure of the AHAS (Arabidopsis thaliana) catalytic subunit in complex with various AHAS inhibitor herbicides have greatly improved current understanding of the detailed molecular interactions between AHAS, cofactors and herbicides. Compared with target-site resistance, non-target-site resistance to AHAS inhibitor herbicides is less studied and hence less understood. In a few well-studied cases, non-target-site resistance is due to enhanced rates of herbicide metabolism (metabolic resistance), mimicking that occurring in tolerant crop species and often involving cytochrome P450 monooxygenases. However, the specific herbicide-metabolising, resistance-endowing genes are yet to be identified in resistant weed species. The current state of mechanistic understanding of AHAS inhibitor herbicide resistance is reviewed, and outstanding research issues are outlined. © 2013 Society of Chemical Industry.

Comparative toxicity of 20 herbicides to 5 periphytic algae and the relationship with mode of action.

PubMed

Nagai, Takashi; Taya, Kiyoshi; Yoda, Ikuko

2016-02-01

The authors used 5 species of periphytic algae to conduct toxicity assays of 20 herbicides. The 5 tested species represent riverine primary producers most likely to be affected by herbicides. A fluorescence microplate toxicity assay was used as an efficient and economical high-throughput assay. Toxicity characteristics were analyzed, focusing on their relationship to herbicide mode of action. The relative differences between 50% and 10% effect concentrations depended on herbicide mode of action, rather than tested species. Moreover, a clear relationship between sensitive species and herbicide mode of action was also observed. Green alga was most sensitive to herbicides of 2 mode of action groups: inhibitors of protoporphyrinogen oxidase and very long-chain fatty acid synthesis. Diatoms were most sensitive to herbicides of 1 mode of action group: 4-hydroxyphenyl-pyruvate-dioxygenase inhibitors. Cyanobacterium was most sensitive to herbicides of 1 mode of action group: inhibitors of acetolactate synthase. The species sensitivity distribution based on obtained data was also analyzed. The slopes of the species sensitivity distribution significantly differed among modes of action, suggesting that difference in species sensitivity is specific to the mode of action. In particular, differences in species sensitivity were markedly large for inhibitors of acetolactate synthase, protoporphyrinogen oxidase, and very long-chain fatty acid synthesis. The results clearly showed that a single algal species cannot represent the sensitivity of an algal assemblage. Therefore, multispecies algal toxicity data are essential for substances with specific modes of action. © 2015 SETAC.

Eight years of seasonal burning and herbicidal brush control influence sapling longleaf pine growth, understory vegetation, and the outcome of an ensuing wildfire

Treesearch

James D. Haywood

2009-01-01

To study how fire or herbicide use influences longleaf pine (Pinus palustris Mill.) overstory and understory vegetation, five treatments were initiated in a 5–6-year-old longleaf pine stand: check, biennial arborescent plant control by directed herbicide application, and biennial burning in March, May, or July. The herbicide or prescribed fire...

Initial response of loblolly pine and competition to mid rotation fertilization and herbicide application in the gulf coastal plain

Treesearch

Hal O. Liechty; Conner Fristoe

2010-01-01

Application of N and P to mid-rotation loblolly pines (Pinus taeda L.) stands is a common silvicultural practice used to increase crop tree production in the Gulf Coastal Plain. Mid-rotation applications of herbicides or combined applications of herbicide and fertilizer are a less common practice. We applied herbicide (1.17 l imazapyr and 0.23 l...

Forty years of spruce–fir stand development following herbicide application and precommercial thinning in central Maine, USA

Treesearch

Matthew G. Olson; Robert G. Wagner; John C. Brissette

2012-01-01

We examined the development of a 33-year experiment in spruce–fir stands that received nine herbicide treatments (applied aerially in 1977), with and without precommercial thinning (PCT) (applied in 1986). We tested two commonly held assumptions about the long-term effects of herbicide and PCT in mixedwood stands managed for softwoods: (i) herbicide release produces...

Development of a mixed shrub-tanoak-Douglas-fir community in a treated and untreated condition

Treesearch

Philip M. McDonald; Gary O. Fiddler

1996-01-01

On a medium site in northern California, a tanoak-mixed shrub community was given several treatments (manual release two and three times, a combination chainsaw and cut surface herbicide treatment, two foliar herbicides, and a tank mix of the two herbicides) to study its development in both a natural (control) and treated condition. The herbicides were 2,4-D, Garlon 3A...

Cumulative effects analysis of the water quality risk of herbicides used for site preparation in the Central North Island, New Zealand

Treesearch

Dan Neary; Brenda R. Baillie

2016-01-01

Herbicide use varies both spatially and temporally within managed forests. While information exists on the effects of herbicide use on water quality at the site and small catchment scale, little is known about the cumulative effects of herbicide use at the landscape scale. A cumulative effects analysis was conducted in the upper Rangitaiki catchment (118,345...

Mechanism of Sulfonylurea Herbicide Resistance in the Broadleaf Weed, Kochia scoparia

PubMed Central

Saari, Leonard L.; Cotterman, Josephine C.; Primiani, Michael M.

1990-01-01

Selection of kochia (Kochia scoparia) biotypes resistant to the sulfonylurea herbicide chlorsulfuron has occurred through the continued use of this herbicide in monoculture cereal-growing areas in the United States. The apparent sulfonylurea resistance observed in kochia was confirmed in greenhouse tests. Fresh and dry weight accumulation in the resistant kochia was 2- to >350-fold higher in the presence of four sulfonylurea herbicides as compared to the susceptible biotype. Acetolactate synthase (ALS) activity isolated from sulfonylurea-resistant kochia was less sensitive to inhibition by three classes of ALS-inhibiting herbicides, sulfonylureas, imidazolinones, and sulfonanilides. The decrease in ALS sensitivity to inhibition (as measured by the ratio of resistant I50 to susceptible I50) was 5- to 28-fold, 2- to 6-fold, and 20-fold for sulfonylurea herbicides, imidazolinone herbicides, and a sulfonanilide herbicide, respectively. No differences were observed in the ALS-specific activities or the rates of [14C]chlorsulfuron uptake, translocation, and metabolism between susceptible and resistant kochia biotypes. The Km values for pyruvate using ALS from susceptible and resistant kochia were 2.13 and 1.74 mm, respectively. Based on these results, the mechanism of sulfonylurea resistance in this kochia biotype is due solely to a less sulfonylurea-sensitive ALS enzyme. PMID:16667465

Runoff of the herbicides triclopyr and glufosinate ammonium from oil palm plantation soil.

PubMed

Tayeb, M A; Ismail, B S; Khairiatul-Mardiana, J

2017-10-11

This study focused on the residue detection of the herbicides triclopyr and glufosinate ammonium in the runoff losses from the Tasik Chini oil palm plantation area and the Tasik Chini Lake under natural rainfall conditions in the Malaysian tropical environment. Triclopyr and glufosinate ammonium are post-emergence herbicides. Both herbicides were foliar-sprayed on 0.5 ha of oil palm plantation plots, which were individualized by an uneven slope of 10-15%. Samples were collected at 1, 3, 7, 15, 30, 45, 60, 90, and 120 days after treatment. The concentrations of both herbicides quickly diminished from those in the analyzed sample by the time of collection. The highest residue levels found in the field surface leachate were 0.031 (single dosage, triclopyr), 0.041 (single dosage, glufosinate ammonium), 0.017 (double dosage, triclopyr), and 0.037 μg/kg (double dosage, glufosinate ammonium). The chromatographic peaks were observed at "0" day treatment (2 h after herbicide application). From the applied active ingredients, the triclopyr and glufosinate losses were 0.025 and 0.055%, respectively. The experimental results showed that both herbicides are less potent than other herbicides in polluting water systems because of their short persistence and strong adsorption onto soil clay particles.

Can we predict diatoms herbicide sensitivities with phylogeny? Influence of intraspecific and interspecific variability.

PubMed

Esteves, Sara M; Keck, François; Almeida, Salomé F P; Figueira, Etelvina; Bouchez, Agnès; Rimet, Frédéric

2017-10-01

Diatoms are used as indicators of freshwater ecosystems integrity. Developing diatom-based tools to assess impact of herbicide pollution is expected by water managers. But, defining sensitivities of all species to multiple herbicides would be unattainable. The existence of a phylogenetic signal of herbicide sensitivity was shown among diatoms and should enable prediction of new species sensitivity. However, diatoms present a cryptic diversity that may lead to variation in their sensitivity to herbicides that would need to be taken into account. Using bioassays, the sensitivity to four herbicides (Atrazine, Terbutryn, Diuron, Isoproturon) was evaluated for 11 freshwater diatom taxa and intraspecific variability was assessed for two of them (Nitzschia palea and Achnanthidium spp.). Intraspecific variability of herbicide sensitivity was always smaller than interspecific variability, but intraspecific variability was more important in N. palea than in Achnanthidium spp. Indeed, one species showed no intraspecific phylogenetic signal (N. palea) whereas the other did (Achnanthidium spp.). On one hand, species boundaries are not set properly for Achnanthidium spp. which encompass several taxa. On the other hand, there is a higher phenotypic plasticity for N. palea. Finally, a phylogenetic signal of herbicide sensitivity was measured at the interspecific level, opening up prospects for setting up reliable biomonitoring tools based on sensitivity prediction, insofar as species boundaries are correctly defined.

Mechanism of sulfonylurea herbicide resistance in the broadleaf weed, Kochia scoparia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saari, L.L.; Cotterman, J.C.; Primiani, M.M.

Selection of kochia (Kochia scoparia) biotypes resistant to the sulfonylurea herbicide chlorsulfuron has occurred through the continued use of this herbicide in monoculture cereal-growing areas in the United States. The apparent sulfonylurea resistance observed in kochia was confirmed in greenhouse tests. Fresh and dry weight accumulation in the resistance kochia was 2- to >350-fold higher in the presence of four sulfonylurea herbicides as compared to the susceptible biotype. Acetolactate synthase (ALS) activity isolated from sulfonylurea-resistant kochia was less sensitive to inhibition by three classes of ALS-inhibiting herbicides, sulfonylureas, imidazolinones, and sulfonanilides. The decrease in ALS sensitivity to inhibition (as measuredmore » by the ratio of resistant I{sub 50} to susceptible I{sub 50}) was 5- to 28-fold, 2- to 6-fold, and 20-fold for sulfonylurea herbicides, imidazolinone herbicides, and a sulfonanilide herbicide, respectively. No differences were observed in the ALS-specific activities or the rates of ({sup 14}C)chlorsulfuron uptake, translocation, and metabolism between susceptible and resistant kochia biotypes. The K{sub m} values for pyruvate using ALS from susceptible and resistant kochia were 2.13 and 1.74 mM, respectively. Based on these results, the mechanism of sulfonylurea resistance in this kochia biotype is due solely to a less sulfonylurea-sensitive ALS enzyme.« less

Potential roles for microbial endophytes in herbicide tolerance in plants.

PubMed

Tétard-Jones, Catherine; Edwards, Robert

2016-02-01

Herbicide tolerance in crops and weeds is considered to be monotrophic, i.e. determined by the relative susceptibility of the physiological process targeted and the plant's ability to metabolise and detoxify the agrochemical. A growing body of evidence now suggests that endophytes, microbes that inhabit plant tissues and provide a range of growth, health and defence enhancements, can contribute to other types of abiotic and biotic stress tolerance. The current evidence for herbicide tolerance being bitrophic, with both free-living and plant-associated endophytes contributing to tolerance in the host plant, has been reviewed. We propose that endophytes can directly contribute to herbicide detoxification through their ability to metabolise xenobiotics. In addition, we explore the paradigm that microbes can 'prime' resistance mechanisms in plants such that they enhance herbicide tolerance by inducing the host's stress responses to withstand the downstream toxicity caused by herbicides. This latter mechanism has the potential to contribute to the growth of non-target-site-based herbicide resistance in weeds. Microbial endophytes already contribute to herbicide detoxification in planta, and there is now significant scope to extend these interactions using synthetic biology approaches to engineer new chemical tolerance traits into crops via microbial engineering. © 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Degradation of 2,4-DB in Argentinean agricultural soils with high humic matter content.

PubMed

Cuadrado, Virginia; Merini, Luciano J; Flocco, Cecilia G; Giulietti, Ana M

2008-01-01

The dissipation of 4-(2,4-dichlorophenoxy) butyric acid (2,4-DB) in high-humic-matter-containing soils from agricultural fields of the Argentinean Humid Pampa region was studied, employing soil microcosms under different experimental conditions. The added herbicide was dissipated almost completely by soils with and without history of herbicide use by day 28. At 500 ppm, both soils showed the same degradation rates; but at 5-ppm concentration, the chronically exposed soil demonstrated a faster degradation of the herbicide. 2,4-DB addition produced increases in herbicide-degrading bacteria of three and 1.5 orders of magnitude in soils with and without history of herbicide use, respectively, in microcosms with 5 ppm. At 500-ppm concentration, the increase in 2,4-DB degraders was five orders of magnitude after 14 days, independent of the history of herbicide use. No differences were observed in either 2,4-DB degradation rates or in degrader bacteria numbers in the presence and absence of alfalfa plants, in spite of some differential characteristics in patterns of 2,4-DB metabolite accumulation. The main factor affecting 2,4-DB degradation rate would be the history of herbicide use, as a consequence of the adaptation of the indigenous microflora to the presence of herbicides in the field.

Herbicides and degradates in shallow aquifers of Illinois: Spatial and temporal trends

USGS Publications Warehouse

Mills, P.C.; Kolpin, D.W.; Scribner, E.A.; Thurman, E.M.

2005-01-01

During the fall of 2000, the occurrence was examined of 16 herbicides and 13 herbicide degradates in samples from 55 wells in shallow aquifers underlying grain producing regions of Illinois. Herbicide compounds with concentrations above 0.05 ??g/L were detected in 56 percent of the samples. No concentrations exceeded regulatory drinking water standards. The six most frequently detected compounds were degradates. Water age was an important factor in determining vulnerability of ground water to transport of herbicide compounds. Unconsolidated aquifers, which were indicated to generally contain younger ground water than bedrock aquifers, had a higher occurrence of herbicides (73 percent of samples) than bedrock aquifers (22 percent). Temporal analysis to determine if changes in concentrations of selected herbicides and degradates could be observed over a near decadal period indicated a decrease in detection frequency (25 to 18 percent) between samplings in 1991 and 2000. Over this period, significant differences in concentrations were observed for atrazine (decrease) and total acetochlor (increase). The increase in acetochlor compound concentrations corresponds to an increase in acetochlor use during the study period, while the decrease in atrazine concentrations corresponds to relatively consistent use of atrazine. Changes in frequency of herbicide detection and concentration do not appear related to changes in land use near sampled wells.

Uses of thaxtomin and thaxtomin compositions as herbicides

DOEpatents

Koivunen, Marja; Marrone, Pamela

2016-12-27

There is a need for a selective, low-risk herbicide that can be used to control weeds in cereal cultures and turf. The present invention discloses that a bacterial secondary metabolite, thaxtomin and optionally another herbicide is an effective herbicide on broadleaved, sedge and grass weeds. Thaxtomin A and structurally similar compounds can be used as natural herbicides to control the germination and growth of weeds in cereal, turf grass, Timothy grass and pasture grass cultures with no phytotoxicity to these crops. As a natural, non-toxic compound, thaxtomin can be used as a safe alternative for weed control in both conventional and organic farming and gardening systems.

76 FR 80872 - Dow AgroScience LLC; Availability of Petition, Plant Pest Risk Assessment, and Environmental...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-27

... the herbicide 2,4-D) and resistance to grass herbicides in the aryloxyphenoxypropionate acetyl...-D) and resistance to grass herbicides in the aryloxyphenoxypropionate acetyl coenzyme A carboxylase...

Effect of herbicide concentration and organic and inorganic nutrient amendment on the mineralization of mecoprop, 2,4-D and 2,4,5-T in soil and aquifer samples.

PubMed

de Lipthay, Julia R; Sørensen, Sebastian R; Aamand, Jens

2007-07-01

The impact of the herbicide concentration (0.10-10,000 microg kg(-1)) and addition of organic and inorganic nutrients on mecoprop, 2,4-D and 2,4,5-T mineralization in aquifer and soil samples was studied in laboratory experiments. Generally, 2,4-D was most rapidly mineralized followed by mecoprop and 2,4,5-T. A shift from non-growth to growth-linked mineralization kinetics was observed in aquifer sediment with 2,4-D concentrations >0.10 microg kg(-1) and mecoprop concentrations >10.0 microg kg(-1). The shift was apparent at higher herbicide concentrations in soil coinciding with a lower bioavailable fraction and a higher herbicide sorption to soil. Herbicide addition did not affect the bacterial density, although 2,4-D and mecoprop applied at 10,000 microg kg(-1) stimulated growth of specific degraders. Generally, nutrient amendments did not stimulate mineralization at the lowest herbicide concentrations. In contrast, the mineralization rate of higher herbicide concentrations was significantly stimulated by the amendment of inorganic nutrients.

Uptake and Accumulation of the Herbicides Chlorsulfuron and Clopyralid in Excised Pea Root Tissue 1

PubMed Central

Devine, Malcolm D.; Bestman, Hank D.; Vanden Born, William H.

1987-01-01

The herbicides chlorsulfuron and clopyralid were taken up rapidly by excised pea root tissue and accumulated in the tissue to concentrations ten and four times those in the external medium, respectively. Uptake was related linearly to external herbicide concentration over a wide concentration range, implying that transport across the membrane is by nonfacilitated diffusion. Uptake of both compounds was influenced by pH, with greatest uptake at low pH. The pH dependence of uptake suggests that the herbicides (both of which are weak acids) are transported across the plasma membrane in the undissociated form, and accumulate in the cytoplasm by an ion trap mechanism. Most of the absorbed herbicide effluxed from the tissue when it was transferred to herbicide-free buffer, indicating that the accumulation was not due to irreversible binding. Consequently, both herbicides remain available for transfer to the phloem. These results can explain the high reported phloem mobility of clopyralid in intact plants. The low phloem mobility of chlorsulfuron must be accounted for by factors that override its ability to accumulate in the symplast. PMID:16665689

Identification and characterization of a novel carboxylesterase (FpbH) that hydrolyzes aryloxyphenoxypropionate herbicides.

PubMed

Wang, Chenghong; Qiu, Jiguo; Yang, Youjian; Zheng, Jinwei; He, Jian; Li, Shunpeng

2017-04-01

To identify and characterize a novel aryloxyphenoxypropionate (AOPP) herbicide-hydrolyzing carboxylesterase from Aquamicrobium sp. FPB-1. A carboxylesterase gene, fpbH, was cloned from Aquamicrobium sp. FPB-1. The gene is 798 bp long and encodes a protein of 265 amino acids. FpbH is smaller than previously reported AOPP herbicide-hydrolyzing carboxylesterases and shares only 21-35% sequence identity with them. FpbH was expressed in Escherichia coli BL21(DE3) and the product was purified by Ni-NTA affinity chromatography. The purified FpbH hydrolyzed a wide range of AOPP herbicides with catalytic efficiency in the order: haloxyfop-P-methyl > diclofop-methyl > fenoxaprop-P-ethyl > quizalofop-P-ethyl > fluazifop-P-butyl > cyhalofop-butyl. The optimal temperature and pH for FpbH activity were 37 °C and 7, respectively. FpbH is a novel AOPP herbicide-hydrolyzing carboxylesterase; it is a good candidate for mechanistic study of AOPP herbicide-hydrolyzing carboxylesterases and for bioremediation of AOPP herbicide-contaminated environments.

Bee genera, diversity and abundance in genetically modified canola fields.

PubMed

O'Brien, Colton; Arathi, H S

2018-01-02

Intensive agricultural practices resulting in large scale habitat loss ranks as the top contributing factors in the global bee decline. Growing Genetically Modified Herbicide Tolerant (GMHT) crops as large monocultures has resulted extensive applications of herbicides leading to the degradation of natural habitats surrounding farmlands. Herbicide tolerance trait is beneficial for crops such as Canola (Brassica napus) that are extremely vulnerable to weed competition. While the trait in itself does not harm pollinators, growing genetically modified herbicide tolerant cultivars indirectly contributes towards pollinator declines through habitat loss. Canola, a mass-flowering crop is highly attractive to bee pollinators and the extensive adoption of the herbicide tolerant trait has led to depletion of non-crop floral resources. Extensive use of herbicide in and near fields with herbicide tolerant cultivars systematically eliminates semi-natural habitats around agricultural fields which consist of non-crop flowering plants. Planting pollinator strips provides floral resources for bees after crop flowering. We document the bee genera in canola and the adjoining pollinator strip. The overlap in bee genera reinforces the importance of pollinator habitats in agricultural landscape.

Application of bioassay technique to determine onduty herbicide resistance in soil

NASA Astrophysics Data System (ADS)

Bakar, F. A. A.; Ismail, B. S.; Bajrai, F. S. M.

2016-11-01

A study was conducted to determine the resistance of OnDuty herbicide in paddy soil with different concentrations by using a broadleaf plant, Brassica juncea. The herbicide was used in the Clearfield® Production System that was adopted in Malaysia to overcome problems mainly caused by weedy rice. Evaluation of herbicide half-life was based on bioassay technique with different concentrations, i.e 0% (control), 50% (half dose), 100% (recommended dose) and 200% (double dose). The study was done in three replicates and followed the Complete Randomized Block Design (CRBD). Results showed that there was a correlation between the amount of herbicide doses and degradation period. The highest half-life value was shown by root inhibition in the double dose concentration of 33 days half-life, followed by the recommended dose with 23 days half-life. Meanwhile, the half dose treatment indicated a half-life value of 17 days for root and 11 days for shoot. Therefore, application of herbicides should follow the recommended dose as the degradation period will not be too long, hence providing maximum effectiveness of the herbicide to overcome weed infestation problems.

77 FR 64988 - Pesticide Experimental Use Permit; Receipt of Application; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-24

... requesting an experimental use permit (EUP) for the herbicides glyphosate and dicamba (M1751 Herbicide). The.../Product: Glyphosate and Dicamba/M1751 Herbicide. Summary of Request: Application for an EUP to conduct...

0-6733 : evaluation of generic and branded herbicides.

DOT National Transportation Integrated Search

2012-08-01

As with other products in the marketplace, : generic herbicides often have a lower initial : product cost than their brand-name : counterparts.Herbicide formulations are : patented for 17 years with proprietary rights for : name, formula, and product...

ANALYTICAL MASS SPECTROMETRY OF HERBICIDES

EPA Science Inventory

Herbicides are chemical substances that are applied to agricultural soils, gardens, lawns, or plants to destroy or to prevent the growth of undesirable vegetation. The herbicides included in this review are generally syntehtic organic compuonds that are ingredients in commercial...

Adsorption and leaching behaviour of bispyribac-sodium in soils.

PubMed

Singh, Neera; Singh, S B

2015-01-01

Adsorption-desorption of the herbicide bispyribac-sodium was studied in four Indian soil types. Bispyribac-sodium was poorly adsorbed in the four soils and adsorption decreased with an increase in the herbicide concentration in solution. Freundlich adsorption coefficient (Kf) values for bispyribac-sodium ranged between 0.37 and 0.87. Slope (1/n) values varied from 0.2 to 0.31 suggesting that bispyribac-sodium adsorption was highly dependent on its initial concentration in solution. Bispyribac-sodium adsorption showed a positive correlation with soil pH (r = 0.809) and clay content (r = 0.699) while no correlation was observed with the organic carbon (r = 0.063) content. Sorbed herbicide was completely desorbed during a single desorption step suggesting that the herbicide was bound by weak adsorptive forces. Leaching studies of herbicide in soil 1 packed column indicated complete loss of soil applied herbicide under a simulated rainfall equivalent to 162 mm.

Influence of long-term used herbicides on resistance development in Apera spica-venti L. to sulfonylureas.

PubMed

Adamczewski, K; Kierzek, R; Matysiak, K

2009-01-01

Sulfonylurea herbicides are widely used for grass and broadleaf weed control in winter cereals in Poland developed resistance, especially in Silky bent grass (Apera spica-venti). The aim of the study was to evaluate the possibility of resistance increase after six years used of some herbicide for control of A. spica-venti in winter cereals monoculture. The field experiments were conducted in Agricultural Experimental Station at Winna Gora. During six years the herbicides: chlorsulfuron, sulfosulfuron, iodosulfuron and isoproturon were applied. In fourth, fifth and sixth years A. spica-venti seed from the experiment was collected and used in greenhouse experiment. The obtained results indicated that after six years usage of the herbicides resistance of A. spica-venti to sulfonylurea herbicides were found. Results obtained in field condition were confirmed in greenhouse experiment. Resistance process was found also on untreated plots. It was indicated that resistance is transferred also by pollen.

Synergistic effects of a combined exposure to herbicides and an insecticide in Hyla versicolor

USGS Publications Warehouse

Mazanti, L.; Sparling, D.W.; Rice, C.; Bialek, K.; Stevenson, C.; Teels, B.; ,

2003-01-01

Combinations of the herbicides atrazine and metolachlor and the insecticide chlorpyrifos were tested under both laboratory and field conditions to determine their individual and combined effects on amphibian populations. In the lab Hyla versicolor tadpoles experienced 100% mortality when exposed to a high combination of the pesticides (2.0 mg/L atrazine, 2.54 mg/L metolachlor, 1.0 mg/L chlorpyrifos) whereas low concentrations of the pesticides (0.2 mg/L atrazine, 0.25 mg/L metolachlor, 0.1 mg/L chlorpyrifos) or high concentrations of either herbicides or insecticide alone caused lethargy, reduced growth and delayed metamorphosis but no significant mortality. In the field high herbicide, low insecticide and low herbicide, low insecticide mixtures significantly reduced amphibian populations compared to controls but in the low herbicide, low insecticide wetlands amphibian populations were able to recover through recruitment by the end of the season.

Deciphering the evolution of herbicide resistance in weeds.

PubMed

Délye, Christophe; Jasieniuk, Marie; Le Corre, Valérie

2013-11-01

Resistance to herbicides in arable weeds is increasing rapidly worldwide and threatening global food security. Resistance has now been reported to all major herbicide modes of action despite the development of resistance management strategies in the 1990s. We review here recent advances in understanding the genetic bases and evolutionary drivers of herbicide resistance that highlight the complex nature of selection for this adaptive trait. Whereas early studied cases of resistance were highly herbicide-specific and largely under monogenic control, cases of greatest concern today generally involve resistance to multiple modes of action, are under polygenic control, and are derived from pre-existing stress response pathways. Although 'omics' approaches should enable unraveling the genetic bases of complex resistances, the appearance, selection, and spread of herbicide resistance in weed populations can only be fully elucidated by focusing on evolutionary dynamics and implementing integrative modeling efforts. Copyright © 2013 Elsevier Ltd. All rights reserved.

Combining experimentalist knowledge with modelling approaches to evaluate a controlled herbicide application experiment in an agricultural headwater catchment

NASA Astrophysics Data System (ADS)

Ammann, Lorenz; Fenicia, Fabrizio; Doppler, Tobias; Reichert, Peter; Stamm, Christian

2017-04-01

Although only a small fraction of the herbicide mass sprayed on agricultural fields reaches the stream in usual conditions, concentrations in streams may reach levels proven to affect organisms. Therefore, diffuse pollution of water bodies by herbicides in catchments dominated by agricultural land-use is a major concern. The process of herbicide wash off has been studied through experiments at lab and field scales. Fewer studies are available at the scales of small catchments and larger watersheds, as the lack of spatial measurements at these scales hinders model parameterization and evaluation. Even fewer studies make explicit use of the combined knowledge of experimentalists and modellers. As a result, the dynamics and interactions of processes responsible for herbicide mobilization and transport at the catchment scale are insufficiently understood. In this work, we integrate preexisting experimentalist knowledge aquired in a large controlled herbicide application experiment into the model development process. The experimental site was a small (1.2 km2) agricultural catchment with subdued topography (423 to 473 m a.s.l.), typical for the Swiss Plateau. The experiment consisted of an application of multiple herbicides, distributed in-stream concentration measurements at high temporal resolution as well as soil and ponding water samples. The measurements revealed considerable spatio-temporal variation in herbicide loss rates. The objective of our study is to better understand the processes that caused this variation. In an iterative dialogue between modellers and experimentalists, we constructed a simple hydrological model structure with multiple reservoirs, considering degradation and sorption of herbicides. Spatial heterogeneity was accounted for through Hydrological Response Units (HRUs). Different model structures were used for dinstinct HRUs to account for spatial variability in the perceived dominant processes. Some parameters were linked between HRUs to constrain the parameter space and facilitate inference. The Superflex hydrological modelling framework provided the flexibility needed for the distributed iterative approach. The model was jointly calibrated to streamflow data and time series of herbicide concentrations. Our preliminary results indicate that herbicide loss rates are generally higher for soils which are prone to saturation or when maximum rainfall intensity is high. While a very simple model is sufficient to characterize the hydrological response of the catchment, considerable extensions are needed to include the major conceptual herbicide transport paths in a physically reasonable way. With the current model we are able to reproduce streamflow dynamics, whereas identifying generalizable mechanisms that drive the wash off dynamics of different herbicides from different fields is challenging.

Protoporphyrin IX Content Correlates with Activity of Photobleaching Herbicides

PubMed Central

Becerril, Jose M.; Duke, Stephen O.

1989-01-01

Several laboratories have demonstrated recently that photobleaching herbicides such as acifluorfen and oxadiazon cause accumulation of protoporphyrin IX (PPIX), a photodynamic pigment capable of herbicidal activity. We investigated, in acifluorfen-treated tissues, the in vivo stability of PPIX, the kinetics of accumulation, and the correlation between concentration of PPIX and herbicidal damage. During a 20 hour dark period, PPIX levels rose from barely detectable concentrations to 1 to 2 nanomoles per 50 cucumber (Cucumis sativus L.) cotyledon discs treated with 10 micromolar acifluorfen. When placed in 500 micromoles per square meter per second PAR, PPIX levels decayed logarithmically, with an initial half-life of about 2.5 hours. PPIX levels at each time after exposure to light correlated positively with the cellular damage that occurred during the following 1 hour in both green and yellow (tentoxin-treated) cucumber cotyledon tissues. PPIX levels in discs incubated for 20 hours in darkness correlated positively with the acifluorfen concentration in which they were incubated. In cucumber, the level of herbicidal damage caused by several p-nitrodiphenyl other herbicides, a p-chlorodiphenylether herbicide, and oxadiazon correlated positively with the amount of PPIX induced to accumulate by each of the herbicide treatments. Similar results were obtained with acifluorfen-treated pigweed and velvetleaf primary leaf tissues. In cucumber, PPIX levels increased within 15 and 30 minutes after exposure of discs to 10 micromolar acifluorfen in the dark and light, respectively. These data strengthen the view that PPIX is responsible for all or a major part of the photobleaching activity of acifluorfen and related herbicides. PMID:16666869

Syntheses and herbicidal activity of new triazolopyrimidine-2-sulfonamides as acetohydroxyacid synthase inhibitor.

PubMed

Chen, Chao-Nan; Chen, Qiong; Liu, Yu-Chao; Zhu, Xiao-Lei; Niu, Cong-Wei; Xi, Zhen; Yang, Guang-Fu

2010-07-15

The triazolopyrimidine-2-sulfonanilide, discovered from preparing bioisosteres of the sulfonylurea herbicides, is an important class of acetohydroxyacid synthase (AHAS, EC 4.1.3.18) inhibitors. At least over ten triazolopyrimidine sulfonanilides have been commercialized as herbicides for the control of broadleaf weeds and grass with cereal crop selectivity. Herein, a series of triazolopyrimidine-2-sulfonanilides were designed and synthesized with the aim of discovery of new herbicides with higher activity. The assay results of the inhibition activity of the synthesized compounds against Arabidopsis thatiana AHAS indicated that some compounds showed a little higher activity against flumetsulam (FS), the first commercial triazolopyrimidine-2-sulfonanilide-type herbicide. The ki values of two promising compounds 3d and 8h are respectively, 1.61 and 1.29 microM, while that of FS is 1.85 microM. Computational simulation results indicated the ester group of compound 3d formed hydrogen bonds with the surrounding residues Arg'198 and Ser653, which accounts for its 11.5-folds higher AHAS inhibition activity than Y6610. Further green house assay showed that compound 3d has comparable herbicidal activity as FS. Even at the concentration of 37.5g.ai/ha, 3d showed excellent herbicidal activity against Galium aparine, Cerastium arvense, Chenopodium album, Amaranthus retroflexus, and Rmumex acetasa, moderate herbicidal activity against Polygonum humifusum, Cyperus iria, and Eclipta prostrate. The combination of in vitro and in vivo assay indicated that 3d could be regarded as a new potential acetohydroxyacid synthase-inhibiting herbicide candidate for further study. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Impact of glyphosate and glyphosate-based herbicides on the freshwater environment.

PubMed

Annett, Robert; Habibi, Hamid R; Hontela, Alice

2014-05-01

Glyphosate [N-(phosphonomethyl) glycine] is a broad spectrum, post emergent herbicide and is among the most widely used agricultural chemicals globally. Initially developed to control the growth of weed species in agriculture, this herbicide also plays an important role in both modern silviculture and domestic weed control. The creation of glyphosate tolerant crop species has significantly increased the demand and use of this herbicide and has also increased the risk of exposure to non-target species. Commercially available glyphosate-based herbicides are comprised of multiple, often proprietary, constituents, each with a unique level of toxicity. Surfactants used to increase herbicide efficacy have been identified in some studies as the chemicals responsible for toxicity of glyphosate-based herbicides to non-target species, yet they are often difficult to chemically identify. Most glyphosate-based herbicides are not approved for use in the aquatic environment; however, measurable quantities of the active ingredient and surfactants are detected in surface waters, giving them the potential to alter the physiology of aquatic organisms. Acute toxicity is highly species dependant across all taxa, with toxicity depending on the timing, magnitude, and route of exposure. The toxicity of glyphosate to amphibians has been a major focus of recent research, which has suggested increased sensitivity compared with other vertebrates due to their life history traits and reliance on both the aquatic and terrestrial environments. This review is designed to update previous reviews of glyphosate-based herbicide toxicity, with a focus on recent studies of the aquatic toxicity of this class of chemicals. Copyright © 2014 John Wiley & Sons, Ltd.

78 FR 44924 - Monsanto Co.; Availability of Plant Pest Risk Assessment, Environmental Assessment, Preliminary...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-25

... Engineered for Herbicide Resistance AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION: Notice... the herbicide glyphosate with more flexibility in the timing of herbicide application. We are also... MON 88302, [[Page 44925

Routine determination of sulfonylurea, imidazolinone, and sulfonamide herbicides at nanogram-per-liter concentrations by solid-phase extraction and liquid chromatography/mass spectrometry

USGS Publications Warehouse

Furlong, E.T.; Burkhardt, M.R.; Gates, Paul M.; Werner, S.L.; Battaglin, W.A.

2000-01-01

Sulfonylurea (SU), imidazolinone (IMI), and sulfonamide (SA) herbicides are new classes of low-application-rate herbicides increasingly used by farmers. Some of these herbicides affect both weed and crop species at low dosages and must be carefully used. Less is known about the effect of these compounds on non-crop plant species, but a concentration of 100 ng/l in water has been proposed as the threshold for possible plant toxicity for most of these herbicides. Hence, analytical methods must be capable of detecting SUs, IMIs, and SAs at concentrations less than 100 ng/l in ambient water samples. The authors developed a two-cartridge, solid-phase extraction method for isolating 12 SU, 3 IMI, and 1 SA herbicides by using high-performance liquid chromatography/electrospray ionization-mass spectrometry (HPLC/ESI-MS) to identify and quantify these herbicides to 10 ng/l. This method was used to analyze 196 surface- and ground-water samples collected from May to August 1998 throughout the Midwestern United States, and more than 100 quality-assurance and quality-control samples. During the 16 weeks of the study, the HPLC/ESI-MS maintained excellent calibration linearity across the calibration range from 5 to 500 ng/l, with correlation coefficients of 0.9975 or greater. Continuing calibration verification standards at 100-ng/l concentration were analyzed throughout the study, and the average measured concentrations for individual herbicides ranged from 93 to 100 ng/l. Recovery of herbicides from 27 reagent-water samples spiked at 50 and 100 ng/l ranged from 39 to 92%, and averaged 73%. The standard deviation of recoveries ranged from 14 to 26%, and averaged 20%. This variability reflects multiple instruments, operators, and the use of automated and manual sample preparation. Spiked environmental water samples had similar recoveries, although for some herbicides, the sample matrix enhanced recoveries by as much as 200% greater than the spiked concentration. This matrix enhancement was sample- and compound-dependent. Concentrations of herbicides in unspiked duplicate environmental samples were typically within 25% of each other. The results demonstrate the usefulness of HPLC/ESI-MS for determining low-application-rate herbicides at ambient concentrations. Copyright (C) 2000 Elsevier Science B.V.

Impacts of forest herbicides on wildlife: Toxicity and habitat alteration

USGS Publications Warehouse

Morrison, M.L.; Meslow, E.C.

1983-01-01

This paper begins with a review of both laboratory and field studies on tbe possible direct toxic effects of herbicides on terrestrial vertebrates, primarily birds and mammals. Alteration of the palatability of forage and changes in reproductive success are also discussed. Emphasis is placed on the use of herbicides in forestry; studies dealing with agricultural systems are referenced where appropriate. The indirect effects of herbicides on wildlife-habitat are then conceptualized and quantified using data from a 3-year study on effects of phenoxy and glyphosate herbicides on bird and small mammal communities in western Oregon. Data on density and habitat use are presented and compared with data available from other geographic regions.

Rationale for a natural products approach to herbicide discovery.

PubMed

Dayan, Franck E; Owens, Daniel K; Duke, Stephen O

2012-04-01

Weeds continue to evolve resistance to all the known modes of herbicidal action, but no herbicide with a new target site has been commercialized in nearly 20 years. The so-called 'new chemistries' are simply molecules belonging to new chemical classes that have the same mechanisms of action as older herbicides (e.g. the protoporphyrinogen-oxidase-inhibiting pyrimidinedione saflufenacil or the very-long-chain fatty acid elongase targeting sulfonylisoxazoline herbicide pyroxasulfone). Therefore, the number of tools to manage weeds, and in particular those that can control herbicide-resistant weeds, is diminishing rapidly. There is an imminent need for truly innovative classes of herbicides that explore chemical spaces and interact with target sites not previously exploited by older active ingredients. This review proposes a rationale for a natural-products-centered approach to herbicide discovery that capitalizes on the structural diversity and ingenuity afforded by these biologically active compounds. The natural process of extended-throughput screening (high number of compounds tested on many potential target sites over long periods of times) that has shaped the evolution of natural products tends to generate molecules tailored to interact with specific target sites. As this review shows, there is generally little overlap between the mode of action of natural and synthetic phytotoxins, and more emphasis should be placed on applying methods that have proved beneficial to the pharmaceutical industry to solve problems in the agrochemical industry. Published 2012 by John Wiley & Sons, Ltd.

Protocols for Robust Herbicide Resistance Testing in Different Weed Species.

PubMed

Panozzo, Silvia; Scarabel, Laura; Collavo, Alberto; Sattin, Maurizio

2015-07-02

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used. Germination methods differ according to weed species and seed dormancy type. Seedlings at similar growth stage are transplanted and maintained in the greenhouse under appropriate conditions until plants have reached the right growth stage for herbicide treatment. Accuracy is required to prepare the herbicide solution to avoid unverifiable mistakes. Other critical steps such as the application volume and spray speed are also evaluated. The advantages of this protocol, compared to others based on whole plant bioassays using one herbicide dose, are related to the higher reliability and the possibility of inferring the resistance level. Quicker and less expensive in vivo or in vitro diagnostic screening tests have been proposed (Petri dish bioassays, spectrophotometric tests), but they provide only qualitative information and their widespread use is hindered by the laborious set-up that some species may require. For routine resistance testing, the proposed whole plant bioassay can be applied at only one herbicide dose, so reducing the costs.

Cross-resistance to prosulfocarb + S-metolachlor and pyroxasulfone selected by either herbicide in Lolium rigidum.

PubMed

Busi, Roberto; Powles, Stephen B

2016-09-01

Weeds can be a greater constraint to crop production than animal pests and pathogens. Pre-emergence herbicides are crucial in many cropping systems to control weeds that have evolved resistance to selective post-emergence herbicides. In this study we assessed the potential to evolve resistance to the pre-emergence herbicides prosulfocarb + S-metolachlor or pyroxasulfone in 50 individual field Lolium rigidum populations collected in a random survey in Western Australia prior to commercialisation of these pre-emergence herbicides. This study shows for the first time that in randomly collected L. rigidum field populations the selection with either prosulfocarb + S-metolachlor or pyroxasulfone can result in concomitant evolution of resistance to both prosulfocarb + S-metolachlor and pyroxasulfone after three generations. In the major weed L. rigidum, traits conferring resistance to new herbicides can be present before herbicide commercialisation. Proactive and multidisciplinary research (evolutionary ecology, modelling and molecular biology) is required to detect and analyse resistant populations before they can appear in the field. Several studies show that evolved cross-resistance in weeds is complex and often unpredictable. Thus, long-term management of cross-resistant weeds must be achieved through heterogeneity of selection by effective chemical, cultural and physical weed control strategies that can delay herbicide resistance evolution. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Broad Resistance to ACCase Inhibiting Herbicides in a Ryegrass Population Is Due Only to a Cysteine to Arginine Mutation in the Target Enzyme

PubMed Central

Kaundun, Shiv Shankhar; Hutchings, Sarah-Jane; Dale, Richard Paul; McIndoe, Eddie

2012-01-01

Background The design of sustainable weed management strategies requires a good understanding of the mechanisms by which weeds evolve resistance to herbicides. Here we have conducted a study on the mechanism of resistance to ACCase inhibiting herbicides in a Lolium multiflorum population (RG3) from the UK. Methodology/Principal Findings Analysis of plant phenotypes and genotypes showed that all the RG3 plants (72%) that contained the cysteine to arginine mutation at ACCase codon position 2088 were resistant to ACCase inhibiting herbicides. Whole plant dose response tests on predetermined wild and mutant 2088 genotypes from RG3 and a standard sensitive population indicated that the C2088R mutation is the only factor conferring resistance to all ten ACCase herbicides tested. The associated resistance indices ranged from 13 for clethodim to over 358 for diclofop-methyl. Clethodim, the most potent herbicide was significantly affected even when applied on small mutant plants at the peri-emergence and one leaf stages. Conclusion/Significance This study establishes the clear and unambiguous importance of the C2088R target site mutation in conferring broad resistance to ten commonly used ACCase inhibiting herbicides. It also demonstrates that low levels “creeping”, multigenic, non target site resistance, is not always selected before single gene target site resistance appears in grass weed populations subjected to herbicide selection pressure. PMID:22768118

Herbicide mixtures at high doses slow the evolution of resistance in experimentally evolving populations of Chlamydomonas reinhardtii.

PubMed

Lagator, Mato; Vogwill, Tom; Mead, Andrew; Colegrave, Nick; Neve, Paul

2013-05-01

The widespread evolution of resistance to herbicides is a pressing issue in global agriculture. Evolutionary principles and practices are key to the management of this threat to global food security. The application of mixtures of herbicides has been advocated as an anti-resistance strategy, without substantial empirical support for its validation. We evolved experimentally populations of the unicellular green chlorophyte, Chlamydomonas reinhardtii, to minimum inhibitory concentrations (MICs) of single-herbicide modes of action and to pair-wise and three-way mixtures between different herbicides at various total combined doses. Herbicide mixtures were most effective when each component was applied at or close to its MIC. When doses were high, increasing the number of mixture components was also effective in reducing the evolution of resistance. Employing mixtures at low combined doses did not retard resistance evolution, even accelerating the evolution of resistance to some components. At low doses, increasing the number of herbicides in the mixture tended to select for more generalist resistance (cross-resistance). Our results reinforce findings from the antibiotic resistance literature and confirm that herbicide mixtures can be very effective for resistance management, but that mixtures should only be employed where the economic and environmental context permits the applications of high combined doses. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Evolution of herbicide resistance mechanisms in grass weeds.

PubMed

Matzrafi, Maor; Gadri, Yaron; Frenkel, Eyal; Rubin, Baruch; Peleg, Zvi

2014-12-01

Herbicide resistant weeds are becoming increasingly common, threatening global food security. Here, we present BrIFAR: a new model system for the functional study of mechanisms of herbicide resistance in grass weeds. We have developed a large collection of Brachypodium accessions, the BrI collection, representing a wide range of habitats. Wide screening of the responses of the accessions to four major herbicide groups (PSII, ACCase, ALS/AHAS and EPSPS inhibitors) identified 28 herbicide-resistance candidate accessions. Target-site resistance to PSII inhibitors was found in accessions collected from habitats with a known history of herbicide applications. An amino acid substitution in the psbA gene (serine264 to glycine) conferred resistance and also significantly affected the flowering and shoot dry weight of the resistant accession, as compared to the sensitive accession. Non-target site resistance to ACCase inhibitors was found in accessions collected from habitats with a history of herbicide application and from a nature reserve. In-vitro enzyme activity tests and responses following pre-treatment with malathion (a cytochrome-P450 inhibitor) indicated sensitivity at the enzyme level, and give strong support to diclofop-methyl and pinoxaden enhanced detoxification as NTS resistance mechanism. BrIFAR can promote better understanding of the evolution of mechanisms of herbicide resistance and aid the implementation of integrative management approaches for sustainable agriculture. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Assessment of Envi-Carb™ as a passive sampler binding phase for acid herbicides without pH adjustment.

PubMed

Seen, Andrew; Bizeau, Oceane; Sadler, Lachlan; Jordan, Timothy; Nichols, David

2014-05-01

The graphitised carbon solid phase extraction (SPE) sorbent Envi-Carb has been used to fabricate glass fibre filter- Envi-Carb "sandwich" disks for use as a passive sampler for acid herbicides. Passive sampler uptake of a suite of herbicides, including the phenoxyacetic acid herbicides 4-chloro-o-tolyloxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 3,6-dichloro-2-methoxybenzoic acid (Dicamba), was achieved without pH adjustment, demonstrating for the first time a suitable binding phase for passive sampling of acid herbicides at neutral pH. Passive sampling experiments with Duck River (Tasmania, Australia) water spiked at 0.5 μg L(-1) herbicide concentration over a 7 d deployment period showed that sampling rates in Duck River water decreased for seven out of eight herbicides, and in the cases of 3,6-dichloro-2-pyridinecarboxylic acid (Clopyralid) and Dicamba no accumulation of the herbicides occurred in the Envi-Carb over the deployment period. Sampling rates for 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (Picloram), 2,4-D and MCPA decreased to approximately 30% of the sampling rates in ultrapure water, whilst sampling rates for 2-(4,6-dimethylpyrimidin-2-ylcarbamoylsulfamoyl) benzoic acid, methyl ester (Sulfometuron-methyl) and 3,5,6-Trichloro-2-pyridinyloxyacetic acid (Triclopyr) were approximately 60% of the ultrapure water sampling rate. For methyl N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-D-alaninate (Metalaxyl-M) there was little variation in sampling rate between passive sampling experiments in ultrapure water and Duck River water. SPE experiments undertaken with Envi-Carb disks using ultrapure water and filtered and unfiltered Duck River water showed that not only is adsorption onto particulate matter in Duck River water responsible for a reduction in herbicide sampling rate, but interactions of herbicides with dissolved or colloidal matter (matter able to pass through a 0.2 μm membrane filter) also reduces the herbicide sampling rate. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Plant reproduction is altered by simulated herbicide drift to constructed plant communities

EPA Science Inventory

Herbicide drift may have unintended impacts on native vegetation, adversely affecting structure and function of plant communities. However, these potential effects have been rarely studied or quantified. To determine potential ecological effects of herbicide drift, we construct...

Impact of irrigation rate on pre-emergence herbicide activity

USDA-ARS?s Scientific Manuscript database

The importance of preemergence herbicide applications in cotton has increased since the development of glyphosate-resistant Palmer amaranth (Amaranthus palmeri). Cotton producers are relying on residual herbicides for control of Palmer amaranth, as postemergence options are limited or ineffective. S...

Agronomic Weeds.

ERIC Educational Resources Information Center

Hartwig, Nathan L.

This agriculture extension service publication from Pennsylvania State University examines agronomic weed problems and control. Contents include a listing of the characteristics of weeds, a section on herbicides, and a section on the important weeds of agronomic crops in Pennsylvania. The herbicide section discusses systemic herbicides, contact…

Evaluation of generic and branded herbicides : technical report.

DOT National Transportation Integrated Search

2015-03-01

As with other generic brand products in the marketplace, generic herbicides often have a lower initial product cost than : their brand-name counterparts. While the purchase price of herbicides is important to TxDOT, it is essential to look at : more ...

Control of Butterfly Bush with Postemergence Herbicides

USDA-ARS?s Scientific Manuscript database

Butterfly bush (Buddleja davidii) is classified as invasive in several parts of the United States. Two experiments were conducted to evaluate the effectiveness of four herbicides and two application methods on postemergence butterfly bush control. The four herbicides included: Roundup (glyphosate)...

Managing the evolution of herbicide resistance

USDA-ARS?s Scientific Manuscript database

Herbicide-resistant (HR) weeds are widespread threats to the sustainability, productivity, and profitability of many cropping systems. Efforts to combat their spread through herbicide rotation schedules have been marginally effective at best. Despite the scope of the problem, we lack sound empirical...

FLAMMABILITY OF HERBICIDE-TREATED GUAVA FOLIAGE

DTIC Science & Technology

Guava leaves treated with herbicide were found to be less flammable than untreated green leaves or dead leaves . Differences in flammability were...determined by small-scale laboratory fires, differential thermal analysis, and thermogravimetric analysis. The herbicide-treated leaves had a higher ash

ASSESSING THE RISKS OF NON-TARGET TERRESTRIAL PLANTS FROM HERBICIDES

EPA Science Inventory

Use of chemical herbicides to reduce weed competition is a major contributing factor to the high productivity of conventional intensive agricultural cropping systems. However, because of their inherent phytotoxicity, movement of herbicides from target crops and soils can adverse...

Herbicide-resistant crop biotechnology: potential and pitfalls

USDA-ARS?s Scientific Manuscript database

Herbicide-resistant crops are an important agricultural biotechnology that can enable farmers to effectively control weeds without harming their crops. Glyphosate-resistant (i.e. Roundup Ready) crops have been the most commercially successful varieties of herbicide-resistant crops and have been plan...

Quantitative proteomics reveals ecological fitness cost of multi-herbicide resistant barnyardgrass (Echinochloa crus-galli L.).

PubMed

Yang, Xia; Zhang, Zichang; Gu, Tao; Dong, Mingchao; Peng, Qiong; Bai, Lianyang; Li, Yongfeng

2017-01-06

Barnyardgrass (Echinochloa crus-galli) is one of the top 15 herbicide-resistant weeds around the world that interferes with rice growth, resulting in major losses of rice yield. Thus, multi-herbicide resistance in barnyardgrass presents a major threat, with the underlying mechanisms that contribute to resistance requiring elucidation. In an attempt to characterize this multi-herbicide resistance at the proteomic level, comparative analysis of resistant and susceptible barnyardgrasses was performed using iTRAQ, both with and without quinclorac, bispyribac-sodium and penoxsulam herbicidal treatment. A total of 1342 protein species were identified from 2248 unique peptides by searching the UniProt database and conducting data analysis. Approximately 904 protein species with 4774 Gene Ontology (GO) terms were grouped into the categories of biological process, cellular component and molecular function. Among these, 688 protein species were annotated into 1583 KEGG pathways, with 980 protein species relating to metabolism and 93 relating to environmental information processing. A total of 292 protein species showed more than a 1.2-fold change in abundance in the resistant biotype relative to the susceptible biotype. Furthermore, herbicide treatment resulted in 157 protein species that showed more than a 1.2-fold change in the resistant biotype. Moreover, physiological analyses demonstrated an ecological fitness cost in the resistant biotype. While some studies have shown a fitness cost to be associated with an altered ecological interaction, our understanding of the fitness costs associated with herbicide resistance are limited. Herein, physiological and proteomic analysis demonstrates herbicide resistance associated ecological fitness cost and potential mechanisms of herbicide-resistance in resistant biotypes of E. crus-galli. The results presented herein have revealed differences in ecological adaptation between resistant and susceptible biotypes in E. crus-galli and provide a fundamental basis enabling the development of new strategies for weed control. Lastly, this is the first large-scale proteomics study to examine herbicide stress responses in different barnyardgrass biotypes. Copyright © 2016 Elsevier B.V. All rights reserved.

VARIABLE RATE APPLICATION OF SOIL HERBICIDES IN ARABLE CROPS: FROM THEORY TO PRACTICE.

PubMed

Heijting, S; Kempenaar, C

2014-01-01

Soil herbicides are applied around crop emergence and kill germinating weeds in the surface layer of the soil. These herbicides play an important role in the chemical management of weeds in major arable crops. From an environmental point of view there is a clear need for smarter application of these chemicals. This paper presents research done in The Netherlands on Variable Rate Application (VRA) of soil herbicides by taking into account spatial variation of the soil. Herbicides adsorbed to soil parameters such as clay or organic matter are not available for herbicidal activity. Decision Support Rules (DSR) describe the relation between the soil parameter and herbicide dosage needed for effectively controlling weeds. Research methods such as greenhouse trials, models and on farm research to develop DSR are discussed and results are presented. Another important ingredient for VRA of soil herbicides is an accurate soil map of the field. Sampling and subsequent interpolation is costly. Soil scans measuring a proxy that is subsequently translated into soil properties such as clay fraction and soil organic matter content offer a quicker way to achieve such maps but validation is needed. DSR is applied to the soil map to get the variable dosage map. The farmer combines this map with the routing, spray volume and spray boom width in the Farm Management Information System (FMIS), resulting in a task file. This task file can subsequently be read by the board computer resulting in a VRA spray map. Reduction in soil herbicide depends on the DSR, the spatial variation and pattern of the soil, the spatial configuration of the routing and the technical advances of the spray equipment. Recently, within the framework the Programma Precisie Landbouw, first steps were made to test and implement this in practice. Currently, theory and practice of VRA of soil herbicides is developed within the research program IJKakker in close cooperation with pioneering farmers in The Netherlands.

Potential microbial toxicity and non-target impact of different concentrations of glyphosate-containing herbicide (GCH) in a model Pervious Paving System.

PubMed

Mbanaso, F U; Coupe, S J; Charlesworth, S M; Nnadi, E O; Ifelebuegu, A O

2014-04-01

Pervious Pavement Systems are Sustainable Drainage devices that meet the three-fold SUDS functions of stormwater quantity reduction, quality improvement and amenity benefits. This paper reports on a study to determine the impact of different concentrations of glyphosate-containing herbicides on non-target microorganisms and on the pollutant retention performance of PPS. The experiment was conducted using 0.0484 m(2) test rigs based on a four-layered design. Previous studies have shown that PPS can trap up to 98.7% of applied hydrocarbons, but results of this study show that application of glyphosate-containing herbicides affected this capability as 15%, 9% and 5% of added hydrocarbons were released by high (7200 mg L(-1)), medium (720 mg L(-1)) and low (72 mg L(-1)) glyphosate-containing herbicides concentrations respectively. The concentrations of nutrients released also indicate a potential for eutrophication if these effluents were to infiltrate into aquifers or be released into surface waters. The effect of glyphosate-containing herbicides application on the bacterial and fungal communities was slightly different; fungi exhibited a "top-down" trend as doses of 7200 mg L(-1) glyphosate-containing herbicides yielded the highest fungal growth whilst those with a concentration of 720 mg L(-1) glyphosate-containing herbicides applied yielded the highest bacterial growth. In the case of protists, doses of glyphosate-containing herbicides above 72 mg L(-1) were fatal, but they survived at the lower concentration, especially the ciliates Colpoda cucullus and Colpoda steinii thus indicating potential for their use as biomarkers of herbicide-polluted environments. Data also showed that at the lowest concentration of glyphosate-containing herbicides (72 mg L(-1)), biodegradation processes may not be affected as all trophic levels required for optimum biodegradation of contaminants were present. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pesticides in Surface Drinking-Water Supplies of the Northern Great Plains

PubMed Central

Donald, David B.; Cessna, Allan J.; Sverko, Ed; Glozier, Nancy E.

2007-01-01

Background Human health anomalies have been associated with pesticide exposure for people living in rural landscapes in the northern Great Plains of North America. Objective The objective of this study was to investigate the occurrence of 45 pesticides in drinking water from reservoirs in this area that received water primarily from snowmelt and rainfall runoff from agricultural crop lands. Methods Water from 15 reservoirs was sampled frequently during the spring pesticide application period (early May to mid-August) and less frequently for the remainder of the year. Drinking water was sampled in early July. Sample extracts were analyzed for pesticide content using mass spectrometric detection. Results We detected two insecticides and 27 herbicides in reservoir water. Consistent detection of a subset of 7 herbicides suggested that atmospheric deposition, either directly or in rain, was the principal pathway from fields to the reservoirs. However, the highest concentrations and number of herbicides in drinking water were associated with runoff from a localized 133-mm rainfall over 15 days toward the end of spring herbicide application. Water treatment removed from 14 to 86% of individual herbicides. Drinking water contained 3–15 herbicides (average, 6.4). Conclusions We estimated the mean annual calculated concentration of herbicides in drinking water to be 75 ng/L (2,4-dichlorophenoxy)acetic acid, 31 ng/L (2-chloro-4-methylphenoxy)acetic acid, 24 ng/L clopyralid, 11 ng/L dichlorprop, 4 ng/L dicamba, 3 ng/L mecoprop, and 1 ng/L bro-moxynil. The maximum total concentration of herbicides in drinking water was 2,423 ng/L. For the seven herbicides with established drinking water guidelines, all concentrations of the individual chemicals were well below their respective guideline. However, guidelines have not been established for the majority of the herbicides found in drinking water or for mixtures of pesticides. PMID:17687445

Assessment of agro-industrial and composted organic wastes for reducing the potential leaching of triazine herbicide residues through the soil.

PubMed

Fenoll, José; Vela, Nuria; Navarro, Ginés; Pérez-Lucas, Gabriel; Navarro, Simón

2014-09-15

In this study, we examined the effect of four different organic wastes--composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)--on the sorption, persistence and mobility of eight symmetrical and two asymmetrical-triazine herbicides: atrazine, propazine, simazine, terbuthylazine (chlorotriazines), prometon (methoxytriazine), prometryn, simetryn, terbutryn (methylthiotriazines), metamitron and metribuzin (triazinones). The downward movement of herbicides was monitored using disturbed soil columns packed with a clay loam soil (Hipercalcic calcisol) under laboratory conditions. For unamended and amended soils, the groundwater ubiquity score (GUS) was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). All herbicides showed medium/high leachability through the unamended soils. The addition of agro-industrial and composted organic wastes at a rate of 10% (w:w) strongly decreased the mobility of herbicides. Sorption coefficients normalized to the total soil organic carbon (KOC) increased in the amended soils. These results suggest that used organic wastes could be used to enhance the retention and reduce the mobility of the studied herbicides in soil. Copyright © 2014 Elsevier B.V. All rights reserved.

Enzyme activity and microorganisms diversity in soil contaminated with the Boreal 58 WG herbicide.

PubMed

Kucharski, Jan; Tomkiel, Monika; Baćmaga, Małgorzata; Borowik, Agata; Wyszkowska, Jadwiga

2016-07-02

Next-generation herbicides are relatively safe when used properly, but the recommended rates are relatively low, which can lead to overdosing. This study evaluated the responses of soil-dwelling microorganisms and soil enzymes to contamination with the Boreal 58 WG herbicide. The analyzed product contains active ingredients flufenacet and isoxaflutole. All tests were performed under laboratory conditions. The analyzed material was sandy clay. Boreal 58 WG was introduced to soil in four doses. Soil without the addition of the herbicide served as the control. The soil was mixed with the tested herbicide, and its moisture content was maintained at 50% of capillary water capacity. Biochemical and microbiological analyses were performed on experimental days 0, 20, 40, 80 and 160. Accidental contamination of soil with the Boreal 58 WG herbicide led to a relatively minor imbalance in the soil microbiological and biochemical profile. The herbicide dose influenced dehydrogenase activity in only 0.84%, urease activity in 2.04%, β-glucosidase activity in 8.26%, catalase activity in 12.40%, arylsulfatase activity in 12.54%, acid phosphatase activity in 42.11%, numbers of organotrophic bacteria in 18.29%, actinomyces counts in 1.31% and fungi counts in 6.86%.

Maize, switchgrass, and ponderosa pine biochar added to soil increased herbicide sorption and decreased herbicide efficacy.

PubMed

Clay, Sharon A; Krack, Kaitlynn K; Bruggeman, Stephanie A; Papiernik, Sharon; Schumacher, Thomas E

2016-08-02

Biochar, a by-product of pyrolysis made from a wide array of plant biomass when producing biofuels, is a proposed soil amendment to improve soil health. This study measured herbicide sorption and efficacy when soils were treated with low (1% w/w) or high (10% w/w) amounts of biochar manufactured from different feedstocks [maize (Zea mays) stover, switchgrass (Panicum vigatum), and ponderosa pine (Pinus ponderosa)], and treated with different post-processing techniques. Twenty-four hour batch equilibration measured sorption of (14)C-labelled atrazine or 2,4-D to two soil types with and without biochar amendments. Herbicide efficacy was measured with and without biochar using speed of seed germination tests of sensitive species. Biochar amended soils sorbed more herbicide than untreated soils, with major differences due to biochar application rate but minor differences due to biochar type or post-process handling technique. Biochar presence increased the speed of seed germination compared with herbicide alone addition. These data indicate that biochar addition to soil can increase herbicide sorption and reduce efficacy. Evaluation for site-specific biochar applications may be warranted to obtain maximal benefits without compromising other agronomic practices.

Pollution-induced community tolerance (PICT) as a tool for monitoring Lake Geneva long-term in situ ecotoxic restoration from herbicide contamination.

PubMed

Larras, Floriane; Rimet, Frédéric; Gregorio, Vincent; Bérard, Annette; Leboulanger, Christophe; Montuelle, Bernard; Bouchez, Agnès

2016-03-01

Chemical monitoring revealed a regular decrease in herbicide concentration in Lake Geneva since last decades that may be linked to an ecotoxic restoration of nontarget phytoplanktonic communities. The Pollution-induced community tolerance (PICT) approach was tested as a tool to monitor the ecotoxic restoration of Lake Geneva for herbicides from 1999 to 2011. We conducted monthly assessments in 1999 and in 2011 for the tolerance of the phytoplankton communities to two herbicides (atrazine and copper), using PICT bioassays. The taxonomical composition of the communities was determined on the same collecting dates. The herbicide concentration decrease during the 12 years significantly influenced the composition of communities. The PICT monitoring indicated that a significant tolerance decrease in the community to both herbicides accompanied the herbicide concentration decrease. PICT measurements for atrazine and copper also changed at the intra-annual level. These variations were mainly due to community composition shifts linked to seasonal phosphorus and temperature changes. PICT monitoring on a seasonal basis is required to monitor the mean tolerance of communities. PICT appeared to be a powerful tool that reflected the toxic effects on environmental communities and to monitor ecotoxic ecosystem restoration.

Crystal structure of plant acetohydroxyacid synthase, the target for several commercial herbicides.

PubMed

Garcia, Mario Daniel; Wang, Jian-Guo; Lonhienne, Thierry; Guddat, Luke William

2017-07-01

Acetohydroxyacid synthase (AHAS, EC 2.2.1.6) is the first enzyme in the branched-chain amino acid biosynthesis pathway. Five of the most widely used commercial herbicides (i.e. sulfonylureas, imidazolinones, triazolopyrimidines, pyrimidinyl-benzoates and sulfonylamino-cabonyl-triazolinones) target this enzyme. Here we have determined the first crystal structure of a plant AHAS in the absence of any inhibitor (2.9 Å resolution) and it shows that the herbicide-binding site adopts a folded state even in the absence of an inhibitor. This is unexpected because the equivalent regions for herbicide binding in uninhibited Saccharomyces cerevisiae AHAS crystal structures are either disordered, or adopt a different fold when the herbicide is not present. In addition, the structure provides an explanation as to why some herbicides are more potent inhibitors of Arabidopsis thaliana AHAS compared to AHASs from other species (e.g. S. cerevisiae). The elucidation of the native structure of plant AHAS provides a new platform for future rational structure-based herbicide design efforts. The coordinates and structure factors for uninhibited AtAHAS have been deposited in the Protein Data Bank (www.pdb.org) with the PDB ID code 5K6Q. © 2017 Federation of European Biochemical Societies.

Changes in bacterial community after application of three different herbicides.

PubMed

Moretto, Jéssica Aparecida Silva; Altarugio, Lucas Miguel; Andrade, Pedro Avelino; Fachin, Ana Lúcia; Andreote, Fernando Dini; Stehling, Eliana Guedes

2017-07-06

The native soil microbiota is very important to maintain the quality of that environment, but with the intensive use of agrochemicals, changes in microbial biomass and formation of large quantities of toxic waste were observed in soil, groundwater and surface water. Thereby, the goal of this study was to evaluate if the selective pressure exerted by the presence of the herbicides atrazine, diuron and 2,4-D changes the bacterial community structure of an agricultural soil, using denaturing gradient gel electrophoresis technique. According to PERMANOVA analysis, a greater effect of the herbicide persistence time in the soil, the effect of the herbicide class and the effect of interaction between these two factors (persistence time and herbicide class) were observed. In conclusion, the results showed that the selective pressure exerted by the presence of these herbicides altered the composition of the local microbiota, being atrazine and diuron that most significantly affected the bacterial community in soil, and the herbicide 2,4-D was the one that less altered the microbial community and that bacterial community was reestablished first. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Strategies to evaluate biodegradability: application to chlorinated herbicides.

PubMed

Sanchis, S; Polo, A M; Tobajas, M; Rodriguez, J J; Mohedano, A F

2014-01-01

The biodegradability of nitrochlorinated (diuron and atrazine) and chlorophenoxy herbicides (2,4-D and MCPA) has been studied through several bioassays using different testing times and biomass/substrate ratios. A fast biodegradability test using unacclimated activated sludge yielded no biodegradation of the herbicides in 24 h. The inherent biodegradability test gave degradation percentages of around 20-30% for the nitrochlorinated herbicides and almost complete removal of the chlorophenoxy compounds. Long-term biodegradability assays were performed using sequencing batch reactor (SBR) and sequencing batch membrane bioreactor (SB-MBR). Fixed concentrations of each herbicide below the corresponding EC50 value for activated sludge were used (30 mg L(-1) for diuron and atrazine and 50 mg L(-1) for 2,4-D and MCPA). No signs of herbicide degradation appeared before 35 days in the case of diuron and atrazine and 21 days for 2,4-D, whereas MCPA was partially degraded since the early stages. Around 25-36% degradation of the nitrochlorinated herbicides and 53-77% of the chlorophenoxy ones was achieved after 180 and 135 days, respectively, in SBR, whereas complete disappearance of 2,4-D was reached after 80 days in SB-MBR.

Analysis of chlorophenoxy acid herbicides in water by large-volume on-line derivatization and gas chromatography-mass spectrometry.

PubMed

Ding, W H; Liu, C H; Yeh, S P

2000-10-27

This work presents a modified method to analyze chlorophenoxy acid herbicides in water samples. The herbicides 2,4-D (2,4-dichlorophenoxyacetic acid). Silvex (2,4,5-trichlorophenoxypropionic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) were used to evaluate the method. The method involves extraction of samples by a graphitized carbon black cartridge, and on-line derivatization in the GC injection port using a large-volume (10-20 microl) direct sample introduction (DSI) device with tetraalkylammonium salts. The analytes were then identified and quantitated by ion-trap gas chromatography-mass spectrometry. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for chlorophenoxy acid herbicides residues, to quantitation at 0.1 to 0.2 microg/l in 500-ml water samples. An enhanced characteristic mass chromatogram of molecular ions of butylated chlorophenoxy acid herbicides with a significant chlorine isotope pattern by electron impact ionization MS allows us to determine herbicides residues at trace levels in aqueous samples. Recovery of the herbicide residues in spiked various water samples ranged from 70 to 99% while RSDs ranged from 1 to 13%.

Herbicide volatilization trumps runoff losses, a multi-year investigation

USDA-ARS?s Scientific Manuscript database

Surface runoff and volatilization are two processes critical to herbicide off-site transport. To determine the relevance of these off-site transport mechanisms, runoff and turbulent vapor fluxes were simultaneously monitored on the same site for eight years. Site location, herbicide formulations, ...

Contaminant Transport to Shallow Drainage Water in Pothole Topography

USDA-ARS?s Scientific Manuscript database

Nutrient and herbicide losses from row crop agriculture represent potential environmental and human health hazards. In order to determine where nutrient and herbicide mitigation strategies can be targeted for optimum performance, levels of nutrients and herbicides were measured in an agricultural dr...

Risk and Prognostic Factors of Inpatient Mortality Associated with Unintentional Insecticide and Herbicide Poisonings: A Retrospective Cohort Study

PubMed Central

Chien, Wu-Chien; Chung, Chi-Hsiang; Jaakkola, Jouni J. K.; Chu, Chi-Ming; Kao, Senyeong; Su, Sui-Lung; Lai, Ching-Huang

2012-01-01

Introduction Pesticide poisoning is an important public health problem worldwide. The study aimed to determine the risk of all-cause and cause-specific inpatient mortality and to identify prognostic factors for inpatient mortality associated with unintentional insecticide and herbicide pesticide poisonings. Methods We performed a retrospective cohort study of 3,986 inpatients recruited at hospitalization between 1999 and 2008 in Taiwan. We used the International Classification of Disease, 9th ed., Clinical Modification external causes of injury codes to classify poisoning agents into accidental poisoning by insecticides and herbicides. Comparisons in mortality rates were made between insecticide poisoning patients and herbicide poisoning patients by using the Cox proportional hazards models to estimate multivariable-adjusted hazard ratios (HRs) and their 95% confidence intervals (CIs). Results There were 168 deaths during 21,583 person-days of follow-up evaluation (7.8 per 1,000 person-days). The major causes of mortality for insecticide poisonings were the toxic effect of organophosphate and coma, and the major causes of mortality for herbicide poisonings were the toxic effect of other pesticides and the toxic effect of organophosphate. The mortality for herbicide exposure was fourfold higher than that for insecticide exposure. The factors associated with inpatient mortality were herbicide poisonings (HR = 4.58, 95% CI 3.29 to 6.37) and receiving mechanical ventilation treatment (HR = 3.85, 95% CI 2.73 to 5.42). Conclusions We demonstrated that herbicides stand out as the dominant agent for poisoning-related fatalities. The control of and limiting access to herbicide agents and developing appropriate therapeutic regimens, including emergency care, should be priorities. PMID:23029146

Effects of a glyphosate-based herbicide and predation threat on the behaviour of agile frog tadpoles.

PubMed

Mikó, Zsanett; Ujszegi, János; Gál, Zoltán; Hettyey, Attila

2017-06-01

The widespread application of pesticides emphasises the importance of understanding the impacts of these chemicals on natural communities. The most commonly applied broad-spectrum herbicides in the world are glyphosate-based herbicides, which have been suggested to induce significant behavioural changes in non-target organisms even at low environmental concentrations. To scrutinize the behavioural effects of herbicide-exposure we exposed agile frog (Rana dalmatina) tadpoles in an outdoor mesocosm experiment to three concentrations of a glyphosate-based herbicide (0, 2 and 6.5mg acid equivalent (a.e.) / L). To assess whether anti-predator behaviour is affected by the pesticide, we combined all levels of herbicide-exposure with three predator treatments (no predator, caged Aeshna cyanea dragonfly larvae or Lissotriton vulgaris newt adults) in a full factorial design. We observed hiding, activity, proximity to the predator cage and vertical position of tadpoles. We found that at the higher herbicide concentration tadpoles decreased their activity and more tadpoles were hiding, and at least at the lower concentration their vertical position was closer to the water surface than in tadpoles of the control treatment. Tadpoles also decreased their activity in the presence of dragonfly larvae, but did not hide more in response to either predator, nor did tadpoles avoid predators spatially. Further, exposure to the herbicide did not significantly influence behavioural responses to predation threat. Our study documents a definite influence of glyphosate-based herbicides on the behaviour of agile frog tadpoles and indicates that some of these changes are similar to those induced by dangerous predators. This may suggest that the underlying physiological mechanisms or the adaptive value of behavioural changes may similar. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of two commercial herbicides on life history traits of a human disease vector, Aedes aegypti, in the laboratory setting.

PubMed

Morris, Alexandra; Murrell, Ebony G; Klein, Talan; Noden, Bruce H

2016-07-01

Some mosquito species utilize the small niches of water that are abundant in farmland habitats. These niches are susceptible to effects from agricultural pesticides, many of which are applied aerially over large tracts of land. One principal form of weed control in agricultural systems involves the development of herbicide-tolerant crops. The impact of sub-agricultural levels of these herbicides on mosquito survival and life-history traits of resulting adults have not been determined. The aim of this study was to test the effect of two commercial herbicides (Beyond and Roundup) on the survivorship, eclosion time, and body mass of Aedes aegypti. First instar A. aegypti larvae were exposed to varying concentrations (270, 550 and 820 μg/m(2) of glyphosate and 0.74, 1.49, 2.24 μL imazamox/m(2)), all treatments being below recommended application rates, of commercial herbicides in a controlled environment and resulting adult mosquitoes were collected and weighed. Exposure to Roundup had a significant negative effect on A. aegypti survivorship at medium and high sub-agricultural application concentrations, and negatively affected adult eclosion time at the highest concentration. However, exposure to low concentrations of Beyond significantly increased A. aegypti survivorship, although adult female mass was decreased at medium sub-agricultural concentrations. These results demonstrate that low concentrations of two different herbicides, which can occur in rural larval habitats as a result of spray drift, can affect the same species of mosquito in both positive and negative ways depending on the herbicide applied. The effects of commercial herbicides on mosquito populations could have an important effect on disease transmission within agricultural settings, where these and other herbicides are extensively applied to reduce weed growth.

Toxicity of Neurons Treated with Herbicides and Neuroprotection by Mitochondria-Targeted Antioxidant SS31

PubMed Central

Reddy, Tejaswini P.; Manczak, Maria; Calkins, Marcus J.; Mao, Peizhong; Reddy, Arubala P.; Shirendeb, Ulziibat; Park, Byung; Reddy, P. Hemachandra

2011-01-01

The purpose of this study was to determine the neurotoxicity of two commonly used herbicides: picloram and triclopyr and the neuroprotective effects of the mitochondria-targeted antioxidant, SS31. Using mouse neuroblastoma (N2a) cells and primary neurons from C57BL/6 mice, we investigated the toxicity of these herbicides, and protective effects of SS1 peptide against picloram and triclopyr toxicity. We measured total RNA content, cell viability and mRNA expression of peroxiredoxins, neuroprotective genes, mitochondrial-encoded electron transport chain (ETC) genes in N2a cells treated with herbicides and SS31. Using primary neurons from C57BL/6 mice, neuronal survival was studied in neurons treated with herbicides, in neurons pretreated with SS31 plus treated with herbicides, neurons treated with SS31 alone, and untreated neurons. Significantly decreased total RNA content, and cell viability in N2a cells treated with picloram and triclopyr were found compared to untreated N2a cells. Decreased mRNA expression of neuroprotective genes, and ETC genes in cells treated with herbicides was found compared to untreated cells. Decreased mRNA expression of peroxiredoxins 1–6 in N2a cells treated with picloram was found, suggesting that picloram affects the antioxidant enzymes in N2a cells. Immunofluorescence analysis of primary neurons revealed that decreased neuronal branching and degenerating neurons in neurons treated with picloram and triclopyr. However, neurons pretreated with SS31 prevented degenerative process caused by herbicides. Based on these results, we propose that herbicides—picloram and triclopyr appear to damage neurons, and the SS31 peptide appears to protect neurons from herbicide toxicity. PMID:21318024

Distinct non-target site mechanisms endow resistance to glyphosate, ACCase and ALS-inhibiting herbicides in multiple herbicide-resistant Lolium rigidum.

PubMed

Yu, Qin; Abdallah, Ibrahim; Han, Heping; Owen, Mechelle; Powles, Stephen

2009-09-01

This study investigates mechanisms of multiple resistance to glyphosate, acetyl-coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS)-inhibiting herbicides in two Lolium rigidum populations from Australia. When treated with glyphosate, susceptible (S) plants accumulated 4- to 6-fold more shikimic acid than resistant (R) plants. The resistant plants did not have the known glyphosate resistance endowing mutation of 5-enolpyruvylshikimate-3 phosphate synthase (EPSPS) at Pro-106, nor was there over-expression of EPSPS in either of the R populations. However, [(14)C]-glyphosate translocation experiments showed that the R plants in both populations have altered glyphosate translocation patterns compared to the S plants. The R plants showed much less glyphosate translocation to untreated young leaves, but more to the treated leaf tip, than did the S plants. Sequencing of the carboxyl transferase domain of the plastidic ACCase gene revealed no resistance endowing amino acid substitutions in the two R populations, and the ALS in vitro inhibition assay demonstrated herbicide-sensitive ALS in the ALS R population (WALR70). By using the cytochrome P450 inhibitor malathion and amitrole with ALS and ACCase herbicides, respectively, we showed that malathion reverses chlorsulfuron resistance and amitrole reverses diclofop resistance in the R population examined. Therefore, we conclude that multiple glyphosate, ACCase and ALS herbicide resistance in the two R populations is due to the presence of distinct non-target site based resistance mechanisms for each herbicide. Glyphosate resistance is due to reduced rates of glyphosate translocation, and resistance to ACCase and ALS herbicides is likely due to enhanced herbicide metabolism involving different cytochrome P450 enzymes.

Bonneville Power Administration Transmission System Vegetation Management Program Draft Environmental Impact Statement

DOE Office of Scientific and Technical Information (OSTI.GOV)

N /A

Bonneville is responsible for maintaining a network of 24,000 kilometers (km) or 15,000 miles (mi.) of electric transmission lines and 350 substations in a region of diverse vegetation. This vegetation can interfere with electric power flow, pose safety problems for us and the public, and interfere with our ability to maintain these facilities. We need to (1) keep vegetation away from the electric facilities; (2) increase the program efficiency and consistency; (3) review herbicide use (under increased public scrutiny); and (4) maximize the range of tools we can use while minimizing environmental impact (Integrated Vegetation Management). This DEIS establishes Planningmore » Steps for managing vegetation for specific projects (to be tiered to this EIS). In addition to No Action (current practice), alternatives are presented for Rights-of-way, Electric Yards, and Non-electric Facilities (landscaping, work yards). Four vegetation control methods are analyzed: manual, mechanical, herbicide, and biological. Also evaluated are 24 herbicide active ingredients and 4 herbicide application techniques (spot, localized, broadcast, and aerial). For rights-of-way, they consider three sets of alternatives: alternative management approaches (time-driven or establishing low-growing plant communities); alternative method packages; and, if herbicides are in a methods package, alternative vegetation selections (noxious weeds, deciduous, or any vegetation). For electric yards, one herbicide-use alternative is considered. For non-electric facilities, two method package alternatives are considered. For rights-of-way, the environmentally preferred alternative(s) would use manual, mechanical, and biological control methods, as well as spot and localized herbicide applications for noxious and deciduous plant species; the BPA-preferred alternative(s) would add broadcast and aerial herbicide applications, and would use herbicides on any vegetation. Both would factor a management approach that fosters low-growing plant communities.« less

Perspectives on transgenic, herbicide-resistant crops in the United States almost 20 years after introduction.

PubMed

Duke, Stephen O

2015-05-01

Herbicide-resistant crops have had a profound impact on weed management. Most of the impact has been by glyphosate-resistant maize, cotton, soybean and canola. Significant economic savings, yield increases and more efficacious and simplified weed management have resulted in widespread adoption of the technology. Initially, glyphosate-resistant crops enabled significantly reduced tillage and reduced the environmental impact of weed management. Continuous use of glyphosate with glyphosate-resistant crops over broad areas facilitated the evolution of glyphosate-resistant weeds, which have resulted in increases in the use of tillage and other herbicides with glyphosate, reducing some of the initial environmental benefits of glyphosate-resistant crops. Transgenic crops with resistance to auxinic herbicides, as well as to herbicides that inhibit acetolactate synthase, acetyl-CoA carboxylase and hydroxyphenylpyruvate dioxygenase, stacked with glyphosate and/or glufosinate resistance, will become available in the next few years. These technologies will provide additional weed management options for farmers, but will not have all of the positive effects (reduced cost, simplified weed management, lowered environmental impact and reduced tillage) that glyphosate-resistant crops had initially. In the more distant future, other herbicide-resistant crops (including non-transgenic ones), herbicides with new modes of action and technologies that are currently in their infancy (e.g. bioherbicides, sprayable herbicidal RNAi and/or robotic weeding) may affect the role of transgenic, herbicide-resistant crops in weed management. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Effects of a glyphosate-based herbicide on the development of Common toads (Bufo bufo L.; Amphibia) at different temperatures

NASA Astrophysics Data System (ADS)

Baier, Fabian; Gruber, Edith; Spangl, Bernhard; Zaller, Johann G.

2016-04-01

Herbicides based on the active ingredient glyphosate are frequently applied in agriculture, horticulture and private gardens all over the world. Recently, leaching of glyphosate or its metabolite (AMPA) into water bodies inhabited by amphibians has been reported. However, very little is known about non-target effects of these herbicides on amphibians and even less is known to what extent different temperatures might alter these effects. Using climate chambers, we investigated the effects of the glyphosate-based herbicide Roundup PowerFlex® (480 g L-1 glyphosate, formulated as 588 g L-1 potassium salt) on the larval development of Common toads (Bufo bufo L.; Amphibia: Anura) under different temperature regimes (15°C vs. 20°C). We established five herbicide concentrations: 0, 1.5, 3, 4 mg acid equivalent L-1 and a 4 mg a.e. L-1 pulse treatment (totally three applications of 1.5, 1.5 and another 1 mg a.e. L-1) at each temperature in a full-factorial design. Each treatment combination was replicated five times, the experiment ran for 24 days. Results showed a highly significant effect of temperature on body length and body width but no effect of herbicide concentration on these growth parameters. Moreover, highly significant interactions between herbicide and temperature on body length and body width were observed suggesting that herbicides had different effects on different temperatures. In conclusion, although Roundup PowerFlex® at the tested concentrations appeared to have no acute toxicity to larvae of Common toads, the observed effects on tadpole morphology will potentially affect competitive interactions in spawning ponds of amphibia. Our findings of herbicide x temperature interactions might become more prevalent when human-induced climate change will lead to more extreme temperatures.

Selectable tolerance to herbicides by mutated acetolactate synthase genes integrated into the chloroplast genome of tobacco.

PubMed

Shimizu, Masanori; Goto, Maki; Hanai, Moeko; Shimizu, Tsutomu; Izawa, Norihiko; Kanamoto, Hirosuke; Tomizawa, Ken-Ichi; Yokota, Akiho; Kobayashi, Hirokazu

2008-08-01

Strategies employed for the production of genetically modified (GM) crops are premised on (1) the avoidance of gene transfer in the field; (2) the use of genes derived from edible organisms such as plants; (3) preventing the appearance of herbicide-resistant weeds; and (4) maintaining transgenes without obstructing plant cell propagation. To this end, we developed a novel vector system for chloroplast transformation with acetolactate synthase (ALS). ALS catalyzes the first step in the biosynthesis of the branched amino acids, and its enzymatic activity is inhibited by certain classes of herbicides. We generated a series of Arabidopsis (Arabidopsis thaliana) mutated ALS (mALS) genes and introduced constructs with mALS and the aminoglycoside 3'-adenyltransferase gene (aadA) into the tobacco (Nicotiana tabacum) chloroplast genome by particle bombardment. Transplastomic plants were selected using their resistance to spectinomycin. The effects of herbicides on transplastomic mALS activity were examined by a colorimetric assay using the leaves of transplastomic plants. We found that transplastomic G121A, A122V, and P197S plants were specifically tolerant to pyrimidinylcarboxylate, imidazolinon, and sulfonylurea/pyrimidinylcarboxylate herbicides, respectively. Transplastomic plants possessing mALSs were able to grow in the presence of various herbicides, thus affirming the relationship between mALSs and the associated resistance to herbicides. Our results show that mALS genes integrated into the chloroplast genome are useful sustainable markers that function to exclude plants other than those that are GM while maintaining transplastomic crops. This investigation suggests that the resistance management of weeds in the field amid growing GM crops is possible using (1) a series of mALSs that confer specific resistance to herbicides and (2) a strategy that employs herbicide rotation.

Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate in ground water in Colorado

USGS Publications Warehouse

Rupert, Michael G.

2003-01-01

Draft Federal regulations may require that each State develop a State Pesticide Management Plan for the herbicides atrazine, alachlor, metolachlor, and simazine. Maps were developed that the State of Colorado could use to predict the probability of detecting atrazine and desethyl-atrazine (a breakdown product of atrazine) in ground water in Colorado. These maps can be incorporated into the State Pesticide Management Plan and can help provide a sound hydrogeologic basis for atrazine management in Colorado. Maps showing the probability of detecting elevated nitrite plus nitrate as nitrogen (nitrate) concentrations in ground water in Colorado also were developed because nitrate is a contaminant of concern in many areas of Colorado. Maps showing the probability of detecting atrazine and(or) desethyl-atrazine (atrazine/DEA) at or greater than concentrations of 0.1 microgram per liter and nitrate concentrations in ground water greater than 5 milligrams per liter were developed as follows: (1) Ground-water quality data were overlaid with anthropogenic and hydrogeologic data using a geographic information system to produce a data set in which each well had corresponding data on atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well construction. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Relations were observed between ground-water quality and the percentage of land-cover categories within circular regions (buffers) around wells. Several buffer sizes were evaluated; the buffer size that provided the strongest relation was selected for use in the logistic regression models. (3) Relations between concentrations of atrazine/DEA and nitrate in ground water and atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well-construction data were evaluated, and several preliminary multivariate models with various combinations of independent variables were constructed. (4) The multivariate models that best predicted the presence of atrazine/DEA and elevated concentrations of nitrate in ground water were selected. (5) The accuracy of the multivariate models was confirmed by validating the models with an independent set of ground-water quality data. (6) The multivariate models were entered into a geographic information system and the probability maps were constructed.

Accelerated biodegradation of a herbicide applied to the roadside environment using adapted soil microorganisms : final report.

DOT National Transportation Integrated Search

1994-06-01

The extent and duration of pollution from herbicide spills and deliberate applications is related to properties of the herbicide and soil. Objectives of this study included the development of experimental procedures and mathematical models to determi...

Controlling herbicide-susceptible, -tolerant and -resistant weeds with microbial bioherbicides

USDA-ARS?s Scientific Manuscript database

The management of weeds is a necessary but expensive challenge. Public concerns of health, safety, and sustainability have increased interest in reducing the use of synthetic chemicals for weed control. Alternatives to chemical herbicides, such as bioherbicides, may offer an alternative to herbicide...

40 CFR 180.317 - Propyzamide; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the herbicide propyzamide, including its metabolites and degradates, in or on the commodities in the... defined in § 180.1(l), are established for residues of the herbicide propyzamide, including its... for indirect or inadvertent residues of the herbicide propyzamide, including its metabolites and...

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... residues of the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the....05 (2) Tolerances are established for residues of the herbicide quizalofop ethyl, including its... the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the commodities in...

40 CFR 180.317 - Propyzamide; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the herbicide propyzamide, including its metabolites and degradates, in or on the commodities in the... defined in § 180.1(l), are established for residues of the herbicide propyzamide, including its... for indirect or inadvertent residues of the herbicide propyzamide, including its metabolites and...

40 CFR 180.420 - Fluridone; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of the herbicide fluridone, including its metabolites and degradates, in or on the commodities in the... the herbicide fluridone, including its metabolites and degradates, in or on the commodities in the... indirect or inadvertent residues of the herbicide fluridone, including its metabolites and degradates, in...

18 CFR 1304.203 - Vegetation management.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) Fertilizers and herbicides shall not be applied within the SMZ or elsewhere on TVA land, except as specifically approved in the Vegetative Management Plan. (m) Restricted use herbicides and pesticides shall not be applied on TVA-owned shoreland except by a State certified applicator. All herbicides and...

75 FR 40857 - Small Business Size Standards: Waiver of the Nonmanufacturer Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-14

... Herbicides, Insecticides, and Fungicides, under Product Service Code (PSC) 6840, under North American... Rule for Herbicides, Insecticides, and Fungicides, under PSC 6840, under NAICS code 325320. The basis... Herbicides, Insecticides, and Fungicides, PSC 6840, under NAICS code 325320, Pesticides and Other...

40 CFR 180.659 - Pyroxasulfone; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... residues of the herbicide pyroxasulfone, including its metabolites and degradates, in or on the commodities... Wheat, grain 0.03 (2) Tolerances are established for residues of the herbicide pyroxasulfone, including..., straw 0.60 (3) Tolerances are established for residues of the herbicide pyroxasulfone, including its...

18 CFR 1304.203 - Vegetation management.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) Fertilizers and herbicides shall not be applied within the SMZ or elsewhere on TVA land, except as specifically approved in the Vegetative Management Plan. (m) Restricted use herbicides and pesticides shall not be applied on TVA-owned shoreland except by a State certified applicator. All herbicides and...

40 CFR 180.184 - Linuron; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Linuron; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide.... Time-limited tolerances are established for residues of the herbicide linuron [3-(3,4-dichlorophenyl)-1... herbicide linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea), including its metabolites and degradates...

40 CFR 180.317 - Propyzamide; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the herbicide propyzamide, including its metabolites and degradates, in or on the commodities in the... defined in § 180.1(l), are established for residues of the herbicide propyzamide, including its... for indirect or inadvertent residues of the herbicide propyzamide, including its metabolites and...

The Effects of Simazine, a Chlorotriazine Herbicide, on Female Pubertal Development

EPA Science Inventory

Several chlorotriazine herbicides, such as atrazine and its metabolites, have been shown to target the neuroendocrine regulation of male and female reproductive development. Simazine is a pre-emergence herbicide used to control broad-leaf weeds and annual grasses on citrus, nuts ...

40 CFR 180.463 - Quinclorac; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of the herbicide quinclorac, including its metabolites and degradates, in or on the commodities in... the herbicide quinclorac, including its metabolites and degradates, in or on the commodity in the...) Section 18 emergency exemptions. Time-limited tolerances are established for residues of the herbicide...

40 CFR 180.317 - Propyzamide; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the herbicide propyzamide, including its metabolites and degradates, in or on the commodities in the... defined in § 180.1(l), are established for residues of the herbicide propyzamide, including its... for indirect or inadvertent residues of the herbicide propyzamide, including its metabolites and...

Tolerance of chickpeas (Cicer arietinum) to postemergence applied broadleaf herbicides

USDA-ARS?s Scientific Manuscript database

Chickpea producers currently have no postemergence (POST) applied herbicides labeled for broadleaf weed control and rely heavily on preemergence (PRE) herbicides to manage weeds. Severe crop losses from broadleaf weed competition and harvest losses from weeds impeding harvest can occur when PRE herb...

Sub-lethal glyphosate exposure alters flowering phenology and causes transient male-sterility in Brassica spp

EPA Science Inventory

Herbicide resistance in weedy plant populations can develop through different mechanisms such as gene flow of herbicide resistant transgenes from crop species into compatible weedy species or by natural evolution of herbicide resistance or tolerance following selection pressure. ...

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... residues of the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the....05 (2) Tolerances are established for residues of the herbicide quizalofop ethyl, including its... the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the commodities in...

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... residues of the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the....05 (2) Tolerances are established for residues of the herbicide quizalofop ethyl, including its... the herbicide quizalofop ethyl, including its metabolites and degradates, in or on the commodities in...

40 CFR 180.420 - Fluridone; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of the herbicide fluridone, including its metabolites and degradates, in or on the commodities in the... the herbicide fluridone, including its metabolites and degradates, in or on the commodities in the... indirect or inadvertent residues of the herbicide fluridone, including its metabolites and degradates, in...

18 CFR 1304.203 - Vegetation management.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) Fertilizers and herbicides shall not be applied within the SMZ or elsewhere on TVA land, except as specifically approved in the Vegetative Management Plan. (m) Restricted use herbicides and pesticides shall not be applied on TVA-owned shoreland except by a State certified applicator. All herbicides and...

Herbicide injury induces dose-dependent DNA methylome alterations in Arabidopsis

USDA-ARS?s Scientific Manuscript database

The emergence of herbicide-resistant weeds is a major threat facing modern agriculture. Over 470 weedy plant populations have developed resistance to herbicides. Traditional evolutionary mechanisms are not always sufficient to explain the rapidity with which certain weed populations adapt in respons...

Factors Influencing Observed Tillage Impacts on Herbicide Transport

USDA-ARS?s Scientific Manuscript database

The widespread use and potential human health effects of the herbicides atrazine and glyphosate have generated interest in establishing how no-tillage impacts loading of these herbicides to runoff water in comparison to other tillage practices. In this study, potentially confounding factors such as ...

Pelargonic acid as a herbicide in sweet bell peppers

USDA-ARS?s Scientific Manuscript database

Pelargonic acid, although not certified as organic, is naturally occurring in many plants, animals, and foods. It is also phytotoxic to plants as a contact herbicide, injuring and killing plants by destroying the cell membrane. Vegetable producers would benefit from additional herbicide options tha...

Comparative effects of glyphosate and atrazine in chloroplast ultrastructure of wheat and downy brome. [Triticum aestivum; Bromus tectorum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auge, R.M.; Gealy, D.R.; Ogg, A.G.

1987-04-01

Developing and mature leaves of winter wheat (Triticum aestivum L. var. Daws) and the weed species downy brome (Bromus tectorum L.) were subjected to 10 mM (foliar application) and 1 mM (root application) herbicide solutions. Glyphosate (N-(phosphonomethyl) glycine) and atrazine (2-chloro-4-(ethyl-amino)-6-(isopropylamino)-s-triazine) were prepared in a carrier composed of 5% soybean oil concentrate, 35% acetone and 60% water. Penetration experiments with /sup 3/H-labelled herbicides assessed what percentage of herbicide entered leaves, and microautoradiography was used to determine qualitatively how much herbicide was present in the sections viewed with TEM. Tissue was excised at 4, 18, 62 and 200 hours, and thenmore » either freeze-substituted or fixed chemically. Ultrastructural effects of each herbicide on chloroplasts from leaves of newly-germinated seedlings and of well-tillered plants are depicted and discussed. Temporal differences in response of chloroplasts to each herbicide are noted.« less

Herbicides as weed control agents: state of the art: I. Weed control research and safener technology: the path to modern agriculture.

PubMed

Kraehmer, Hansjoerg; Laber, Bernd; Rosinger, Chris; Schulz, Arno

2014-11-01

The purpose of modern industrial herbicides is to control weeds. The species of weeds that plague crops today are a consequence of the historical past, being related to the history of the evolution of crops and farming practices. Chemical weed control began over a century ago with inorganic compounds and transitioned to the age of organic herbicides. Targeted herbicide research has created a steady stream of successful products. However, safeners have proven to be more difficult to find. Once found, the mode of action of the safener must be determined, partly to help in the discovery of further compounds within the same class. However, mounting regulatory and economic pressure has changed the industry completely, making it harder to find a successful herbicide. Herbicide resistance has also become a major problem, increasing the difficulty of controlling weeds. As a result, the development of new molecules has become a rare event today. © 2014 American Society of Plant Biologists. All Rights Reserved.

Herbicides as Weed Control Agents: State of the Art: I. Weed Control Research and Safener Technology: The Path to Modern Agriculture

PubMed Central

Kraehmer, Hansjoerg; Laber, Bernd; Rosinger, Chris; Schulz, Arno

2014-01-01

The purpose of modern industrial herbicides is to control weeds. The species of weeds that plague crops today are a consequence of the historical past, being related to the history of the evolution of crops and farming practices. Chemical weed control began over a century ago with inorganic compounds and transitioned to the age of organic herbicides. Targeted herbicide research has created a steady stream of successful products. However, safeners have proven to be more difficult to find. Once found, the mode of action of the safener must be determined, partly to help in the discovery of further compounds within the same class. However, mounting regulatory and economic pressure has changed the industry completely, making it harder to find a successful herbicide. Herbicide resistance has also become a major problem, increasing the difficulty of controlling weeds. As a result, the development of new molecules has become a rare event today. PMID:25104723

The development of a phosphite-mediated fertilization and weed control system for rice.

PubMed

Manna, Mrinalini; Achary, V Mohan M; Islam, Tahmina; Agrawal, Pawan K; Reddy, Malireddy K

2016-04-25

Fertilizers and herbicides are two vital components of modern agriculture. The imminent danger of phosphate reserve depletion and multiple herbicide tolerance casts doubt on agricultural sustainability in the future. Phosphite, a reduced form of phosphorus, has been proposed as an alternative fertilizer and herbicide that would address the above problems to a considerable extent. To assess the suitability of a phosphite-based fertilization and weed control system for rice, we engineered rice plants with a codon-optimized ptxD gene from Pseudomonas stutzeri. Ectopic expression of this gene led to improved root growth, physiology and overall phenotype in addition to normal yield in transgenic plants in the presence of phosphite. Phosphite functioned as a translocative, non-selective, pre- and post-emergent herbicide. Phosphite use as a dual fertilizer and herbicide may mitigate the overuse of phosphorus fertilizers and reduce eutrophication and the development of herbicide resistance, which in turn will improve the sustainability of agriculture.

A Clomazone Immunoassay to Study the Environmental Fate of the Herbicide in Rice (Oryza sativa) Agriculture

PubMed Central

Carlomagno, M.; Mathó, C.; Cantou, G.; Sanborn, J. R.; Last, J. A.; Hammock, B. D.; Roel, A.; González, D.; González-Sapienza, G.

2010-01-01

The environmental impact of rice agriculture is poorly studied in developing countries, mainly, due to limitations of the analytical capacity. Here we report the development of a clomazone ELISA as a fast and cost-effective tool to monitor the dissipation of this herbicide along the harvest. Antibodies were prepared using different strategies of hapten conjugation, and the best hapten/antibody pair was selected. It proved to be a reliable tool to measure the herbicide in the 2.0-20 ng/mL range in field samples, with excellent correlation with HPLC results. The assay was used to study the dissipation of the herbicide in floodwater of experimental rice paddies in Uruguay. Large differences in the residual amount of herbicide were observed depending on the flooding practices. Due to its robustness and simplicity, the assay may be useful to delineate and monitor management practices that can contribute to minimizing the release of the herbicide in the environment. PMID:20302341

Herbicide resistance work in the United States Department of Agriculture-Agricultural Research Service.

PubMed

Vaughn, Kevin C

2003-01-01

Herbicide-resistant weed biotypes are an increasing problem in agriculture, with reports of resistance to almost every herbicide class at some place in the world, and the total number of resistant biotypes at over 250. Agricultural Research Service (ARS) scientists have been key players in this area since the first substantiated occurrence of these resistant biotypes in the 1970s. The most significant of their contributions is the complete unraveling of the mechanism of triazine resistance by Arntzen and colleagues, then with ARS at the University of Illinois. These studies established a high benchmark for research in this area and are a model for all studies in this area. Other ARS scientists have investigated a large number of weed biotypes with resistance to a wide range of herbicide classes and mechanisms of resistance. Collectively, these studies have been used to generate herbicide resistance-management schemes for growers, based upon the herbicide site and the potential for resistance development.

The development of a phosphite-mediated fertilization and weed control system for rice

PubMed Central

Manna, Mrinalini; Achary, V. Mohan M.; Islam, Tahmina; Agrawal, Pawan K.; Reddy, Malireddy K.

2016-01-01

Fertilizers and herbicides are two vital components of modern agriculture. The imminent danger of phosphate reserve depletion and multiple herbicide tolerance casts doubt on agricultural sustainability in the future. Phosphite, a reduced form of phosphorus, has been proposed as an alternative fertilizer and herbicide that would address the above problems to a considerable extent. To assess the suitability of a phosphite-based fertilization and weed control system for rice, we engineered rice plants with a codon-optimized ptxD gene from Pseudomonas stutzeri. Ectopic expression of this gene led to improved root growth, physiology and overall phenotype in addition to normal yield in transgenic plants in the presence of phosphite. Phosphite functioned as a translocative, non-selective, pre- and post-emergent herbicide. Phosphite use as a dual fertilizer and herbicide may mitigate the overuse of phosphorus fertilizers and reduce eutrophication and the development of herbicide resistance, which in turn will improve the sustainability of agriculture. PMID:27109389

Comprehensive understanding of acetohydroxyacid synthase inhibition by different herbicide families.

PubMed

Garcia, Mario D; Nouwens, Amanda; Lonhienne, Thierry G; Guddat, Luke W

2017-02-14

Five commercial herbicide families inhibit acetohydroxyacid synthase (AHAS, E.C. 2.2.1.6), which is the first enzyme in the branched-chain amino acid biosynthesis pathway. The popularity of these herbicides is due to their low application rates, high crop vs. weed selectivity, and low toxicity in animals. Here, we have determined the crystal structures of Arabidopsis thaliana AHAS in complex with two members of the pyrimidinyl-benzoate (PYB) and two members of the sulfonylamino-carbonyl-triazolinone (SCT) herbicide families, revealing the structural basis for their inhibitory activity. Bispyribac, a member of the PYBs, possesses three aromatic rings and these adopt a twisted "S"-shaped conformation when bound to A. thaliana AHAS ( At AHAS) with the pyrimidinyl group inserted deepest into the herbicide binding site. The SCTs bind such that the triazolinone ring is inserted deepest into the herbicide binding site. Both compound classes fill the channel that leads to the active site, thus preventing substrate binding. The crystal structures and mass spectrometry also show that when these herbicides bind, thiamine diphosphate (ThDP) is modified. When the PYBs bind, the thiazolium ring is cleaved, but when the SCTs bind, ThDP is modified to thiamine 2-thiazolone diphosphate. Kinetic studies show that these compounds not only trigger reversible accumulative inhibition of AHAS, but also can induce inhibition linked with ThDP degradation. Here, we describe the features that contribute to the extraordinarily powerful herbicidal activity exhibited by four classes of AHAS inhibitors.

Comprehensive understanding of acetohydroxyacid synthase inhibition by different herbicide families

PubMed Central

Nouwens, Amanda; Lonhienne, Thierry G.; Guddat, Luke W.

2017-01-01

Five commercial herbicide families inhibit acetohydroxyacid synthase (AHAS, E.C. 2.2.1.6), which is the first enzyme in the branched-chain amino acid biosynthesis pathway. The popularity of these herbicides is due to their low application rates, high crop vs. weed selectivity, and low toxicity in animals. Here, we have determined the crystal structures of Arabidopsis thaliana AHAS in complex with two members of the pyrimidinyl-benzoate (PYB) and two members of the sulfonylamino-carbonyl-triazolinone (SCT) herbicide families, revealing the structural basis for their inhibitory activity. Bispyribac, a member of the PYBs, possesses three aromatic rings and these adopt a twisted “S”-shaped conformation when bound to A. thaliana AHAS (AtAHAS) with the pyrimidinyl group inserted deepest into the herbicide binding site. The SCTs bind such that the triazolinone ring is inserted deepest into the herbicide binding site. Both compound classes fill the channel that leads to the active site, thus preventing substrate binding. The crystal structures and mass spectrometry also show that when these herbicides bind, thiamine diphosphate (ThDP) is modified. When the PYBs bind, the thiazolium ring is cleaved, but when the SCTs bind, ThDP is modified to thiamine 2-thiazolone diphosphate. Kinetic studies show that these compounds not only trigger reversible accumulative inhibition of AHAS, but also can induce inhibition linked with ThDP degradation. Here, we describe the features that contribute to the extraordinarily powerful herbicidal activity exhibited by four classes of AHAS inhibitors. PMID:28137884

A Powerful Molecular Engineering Tool Provided Efficient Chlamydomonas Mutants as Bio-Sensing Elements for Herbicides Detection

PubMed Central

Lambreva, Maya D.; Giardi, Maria Teresa; Rambaldi, Irene; Antonacci, Amina; Pastorelli, Sandro; Bertalan, Ivo; Husu, Ivan; Johanningmeier, Udo; Rea, Giuseppina

2013-01-01

This study was prompted by increasing concerns about ecological damage and human health threats derived by persistent contamination of water and soil with herbicides, and emerging of bio-sensing technology as powerful, fast and efficient tool for the identification of such hazards. This work is aimed at overcoming principal limitations negatively affecting the whole-cell-based biosensors performance due to inadequate stability and sensitivity of the bio-recognition element. The novel bio-sensing elements for the detection of herbicides were generated exploiting the power of molecular engineering in order to improve the performance of photosynthetic complexes. The new phenotypes were produced by an in vitro directed evolution strategy targeted at the photosystem II (PSII) D1 protein of Chlamydomonas reinhardtii, using exposures to radical-generating ionizing radiation as selection pressure. These tools proved successful to identify D1 mutations conferring enhanced stability, tolerance to free-radical-associated stress and competence for herbicide perception. Long-term stability tests of PSII performance revealed the mutants capability to deal with oxidative stress-related conditions. Furthermore, dose-response experiments indicated the strains having increased sensitivity or resistance to triazine and urea type herbicides with I50 values ranging from 6×10−8 M to 2×10−6 M. Besides stressing the relevance of several amino acids for PSII photochemistry and herbicide sensing, the possibility to improve the specificity of whole-cell-based biosensors, via coupling herbicide-sensitive with herbicide-resistant strains, was verified. PMID:23613953

Multiple-Herbicide Resistance Is Widespread in Roadside Palmer Amaranth Populations.

PubMed

Bagavathiannan, Muthukumar V; Norsworthy, Jason K

2016-01-01

Herbicide-resistant Palmer amaranth is a widespread issue in row-crop production in the Midsouthern US. Palmer amaranth is commonly found on roadside habitats in this region, but little is known on the degree of herbicide resistance in these populations. Herbicide resistance in roadside Palmer amaranth populations can represent the spread of an adaptive trait across a selective landscape. A large-scale survey was carried out in the Mississippi Delta region of eastern Arkansas to document the level of resistance in roadside Palmer amaranth populations to pyrithiobac and glyphosate, two important herbicides with broad history of use in the region. A total of 215 Palmer amaranth populations collected across 500 random survey sites were used in the evaluations. About 89 and 73% of the surveyed populations showed >90% survival to pyrithiobac and glyphosate, respectively. Further, only 3% of the populations were completely susceptible to glyphosate, while none of the populations was completely controlled by pyrithiobac. Among the 215 populations evaluated, 209 populations showed multiple resistance to both pyrithiobac and glyphosate at varying degrees. Dose-response assays confirmed the presence of high levels of herbicide resistance in the five selected populations (≥ 25-fold compared to a susceptible standard). Results demonstrate the prevalence of multiple-herbicide resistance in roadside Palmer amaranth populations in this region. Growers should be vigilant of Palmer amaranth infestation in roadsides adjacent to their fields and implement appropriate control measures to prevent likely spread of herbicide resistance into their fields.

Effects of diquat and fomesafen applied alone and in combination with a nonylphenol polyethoxylate adjuvant on Lemna minor in aquatic indoor microcosms.

PubMed

Gorzerino, Caroline; Quemeneur, Alphonse; Hillenweck, Anne; Baradat, Maryse; Delous, Georges; Ollitrault, Martine; Azam, Didier; Caquet, Thierry; Lagadic, Laurent

2009-03-01

The influence of tank-mix adjuvants on pesticide toxicity remains largely unknown. Agral 90, a nonylphenol polyethoxylated tank-mix adjuvant, has been used with diquat (bipyridylium herbicide) and fomesafen (diphenyl-ether herbicide) in aquatic indoor microcosms in order to compare the toxicity of the single compounds and of binary herbicide-adjuvant mixtures to Lemna minor. Twenty-four microcosms were used and treatments were performed with substances alone or with herbicide-adjuvant binary mixtures, at two concentrations levels (44.4 and 222.2 microg/L for the herbicides, and 100 and 500 microg/L for Agral 90). Toxicity was assessed weekly for 1 month through growth measurements, as inferred from the relative frond number (RFN) and relative frond area (RFA). Concentrations of diquat and fomesafen in water and sediments were measured weekly. The herbicides showed very different behaviour in microcosms, with a rapid disappearance of diquat from the aqueous phase whereas fomesafen levels remained almost constant over time. Diquat strongly inhibited the growth of L. minor whereas fomesafen had no effect on plant growth. Presence of the adjuvant only slightly reduced the effect of the lowest concentration of diquat, probably as a result of dispersion of the herbicide at the water surface. It is concluded that tank-mix adjuvant designed to improve herbicide efficiency in the terrestrial environment did not have any effect on aquatic plants when applied to the aquatic environment.

Rapid and sensitive detection of the phenoxy acid herbicides in environmental water samples by magnetic solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Peng, Mao-Min; Han, Ya-Quan; Xia, Hong; Hu, Xi-Zhou; Zhou, You-Xiang; Peng, Li-Jun; Peng, Xi-Tian

2018-05-01

Phenoxy acid herbicides are widely used herbicides that play an important role in improving the yield and quality of crops. However, some research has shown that this kind of herbicide is poisonous to human and animals. In this study, a rapid and sensitive method was developed for the detection of seven phenoxy acid herbicides in water samples based on magnetic solid-phase extraction followed by liquid chromatography and tandem mass spectrometry. Magnetic amino-functionalized multiwalled carbon nanotubes were prepared by mixing bare magnetic Fe 3 O 4 nanoparticles with commercial amino-functionalized multiwalled carbon nanotubes in water. Then the amino-functionalized multiwalled carbon nanotubes were used to enrich phenoxy acid herbicides from water samples based on hydrophobic and ionic interactions. The effects of experimental variables on the extraction efficiency have been studied in detail. Under the optimized conditions, the method validation was performed. Good linearities for seven phenoxy acid herbicides were obtained with squared regression coefficients ranging from 0.9971 to 0.9989. The limits of detection ranged from 0.01 to 0.02 μg/L. The method recoveries of seven phenoxy acid herbicides spiked at three concentration levels in a blank sample were from 92.3 to 103.2%, with inter- and intraday relative standard deviations less than 12.6%. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The growing need for biochemical bioherbicides

USDA-ARS?s Scientific Manuscript database

The volume of herbicide use outpaces that of other pesticides. Evolution of resistance to the currently used herbicides has greatly increased the need for new modes of action (MOAs). More than 20 years have passed since the last new herbicide MOA was introduced. Natural products offer a source of...